Architecture

Architecture is the art and technology of building. But it is much more than that. Buildings reflect the beliefs, aspirations, and culture of the people who construct them. Over the centuries, most of the world's best-known buildings have been made for those with wealth and power. These included pharaohs, kings, popes, and, more recently, governments and corporations. Today, however, architectural historians also recognize the value of vernacular architecture. These are structures built by and for ordinary people.

Architects are those who design buildings. They must be both artists and technicians. Buildings must be pleasing in appearance. But they also must meet practical requirements. They must be of sound construction, and they must be well suited to their function.

We know the history of architecture mainly through the structures themselves. Many buildings continue to stand today, including some that are thousands of years old. Other important structures have fallen or been torn down. They must be studied through written records or archaeological excavations. Architectural historians also study the lives and activities of the people who built the structures. That way they can understand architecture in its context.

The first human settlements that consisted of structures more complex than caves or primitive wooden huts emerged about 6000 B.C. in the ancient Middle East. There, people settled in well-watered, fertile areas and began to farm. With permanent settlements came the need for permanent shelters. Archaeological excavations of ancient towns in present-day Jordan and Turkey provide some of the best evidence of these early agricultural settlements. Houses were made of mud bricks and timber frames. They were clustered together for stability and protection from invaders. Among the houses were shrines with colorfully painted walls decorated with bulls' heads and horns.

The Sumerians were a people who lived in an ancient Middle Eastern region known as Mesopotamia. About 3000 B.C., they began building large cities. At the center of these cities were large temple compounds. The compounds were dominated by stepped structures called ziggurats . The ziggurats were constructed out of sun-dried mud bricks. This style of architecture and city design was adopted by later Mesopotamian people, including the Akkadians and the Babylonians.

The Babylonians adorned their palaces with brightly colored glazed tiles. The Ishtar Gate is part of a fortified wall that surrounded the city of Babylon during the late 500's B.C. It was covered with colorful tiles forming lively patterns and sculptures of animals that projected slightly from the flat background. This technique is known as low relief or bas relief.

The best-known examples of ancient architecture are the monumental pyramids and temples built by the ancient Egyptians. Several of them have survived to the present day.

Until about 3100 B.C., the Egyptians buried their royalty under rectangular mud brick structures with slanted sides and flat tops. These tombs were called mastabas. They were often clustered together and housed the burials of entire royal families.

A new kind of tomb was developed during the 2600's B.C. by Imhotep, the first architect known to history. He built a tomb for King Zoser at the city of Saqqara. The tomb was essentially a series of mastabas stacked one on top of the other and decreasing in size from bottom to top. This was the earliest known pyramid. And it was the first structure ever built with massive blocks of cut stone. Because each side of this pyramid resembled a series of steps, it came to be known as the Step Pyramid.

The three famous pyramids of Giza were built between 2660 and 2560 B.C. They were constructed out of massive limestone blocks. The largest of the three pyramids measures 756 feet (230 meters) on each side. It originally reached a height of 481 feet (147 meters). Its base covers 13 acres (5.2 hectares).

Later Egyptian pyramids were built of mud brick and only encased in stone. After about 1640 B.C., the Egyptians stopped building pyramids. They turned to carving tombs in hillsides or valley floors.

The ancient Egyptians also built many temples. Queen Hatshepsut's funerary temple at Deir el-Bahri is located across the Nile River from Luxor. It is one of the most magnificent temples still in existence. Carved into the side of a towering limestone cliff about 1470 B.C., it features a series of terraces supported by rows of columns, or colonnades, and connected by ramps.

Freestanding temples built at Luxor and Karnak were meant to honor important people during their lifetimes. At the center of these temples were large halls surrounded by colonnades. The central section of the hall, called the hypostyle hall, was taller than the side sections. Its raised ceiling had side openings to allow in light. This was the earliest known example of a clerestory. The clerestory and other formal characteristics of ancient Egyptian temples influenced the development of classical achitecture in Greece and, later, Rome.

China's history is marked by a long series of dynasties and emperors. However, throughout this long history, Chinese architecture changed very little in style or materials used.

The earliest Chinese structures, including tombs and city walls, were built of packed earth and timber frames. During the early 200's B.C., methods of framing with timber became more advanced. Structures with two levels, or stories, became common. These structures typically had peaked, tiled roofs with wide eaves to provide shelter from rain. The wooden beams and supporting brackets were decoratively carved.

With the introduction of Buddhism in the 500's, pagodas became a staple of Chinese architecture. (Pagodas are shrines for Buddhist relics). The pagodas were made of timber or brick. They consisted of several stories with gently sloping roofs.

Chinese architecture reached its peak with the Forbidden City. This vast complex of about 9,000 buildings in the center of Beijing was built over a span of 500 years, beginning in 1368, as a home for the emperors. The timber and brick structures were lavishly decorated with ceramic tiles, red and gold lacquer, enamel, carved wood, and stone and jade inlays.

Perhaps the most famous Chinese structure is the Great Wall of China. It was begun in 214 B.C. to protect China from invasion. The wall was extended and rebuilt many times over the years. The sections existing today were built between the late 1300's and the mid-1600's. Made of packed earth encased in brick and stone, the wall wound across mountains and through valleys for some 4,000 miles (6,400 kilometers). Towers were erected at regular intervals along the wall. They were used as guard posts and platforms from which smoke signals were sent to warn of approaching enemy forces.

Japanese architecture was influenced by the traditions of China, Buddhism, and Shinto, the native religion of Japan. Shinto shrines were finely crafted wood structures with thatched roofs. Since ancient times, they have been torn down and rebuilt on the same plan every twenty years.

Japanese domestic architecture, from teahouses to the Katsura Villa in Kyoto (1615-63), was simple and undecorated but finely crafted. Houses had wood frames and pitched roofs with wide eaves. Inside, rooms often had built-in bookshelves and were separated by screens of fabric or paper. The dimensions of all parts of the Japanese house were based on the proportions of the traditional Japanese straw mat called a tatami. These mats were 3 feet (1 meter) wide by 6 feet (2 meters) long.

Indian architecture reflects many religious and cultural traditions. Buddhists cut temples into rock cliffs and built mud brick mounds, called stupas, from the 200's B.C. to about A.D. 800. Beginning about 600, Hindus built freestanding, rock-cut temples as residences for their gods. India is also home to an Islamic tradition, which can be seen in the famous Taj Mahal. Completed at Agra in 1648, the Taj Mahal is a tomb of gleaming white marble built by a Mogul ruler for his deceased wife. Its great central dome is surrounded by four smaller ones. A slender tower, or minaret, rises from each corner of the marble terrace. The tomb's inner walls are inscribed with verses from the Koran.

The architecture of ancient Latin America is called pre-Columbian. This refers to the time before the arrival of Columbus and other European explorers. Between about A.D. 100 and 800, the Zapotec and Maya people founded rich cultures in the areas of present-day Mexico and Central America. Their towns of stone and wood buildings were laid out in alignment with the patterns of the stars in the night sky. Farther south, in parts of present-day Peru, the Incas built a highly advanced society. They were masters of engineering. About 1450, they built Machu Picchu. Machu Picchu is a vast complex of terraced structures high in the Andes. It served as a country estate for Inca royalty.

The arrival of Europeans beginning in the late 1400's marked a distinct change in the region. European cultural traditions gradually replaced those of the native people. In the 1600's and 1700's, Spanish colonizers brought Europe's baroque style to Latin America. This style was characterized by a sense of movement and drama. It would define Latin American architecture into the modern era.

The architecture of northern Africa includes the pyramids and temples of ancient Egypt as well as the mosques built by Islamic peoples. The architecture of sub-Saharan Africa has only recently been well studied. It includes temporary beehive-shaped structures made of branches, leaves, and other natural materials built by nomadic peoples. More permanent structures, including large mosques and palaces, were built of mud brick over bamboo frames.

Perhaps the most notable ancient African structure south of the Sahara is the fortified city of Great Zimbabwe (from which the country Zimbabwe took its name). The site today consists of several immense walls built of granite blocks and a tall conical tower resembling a grain silo.

More than any civilization before them, the ancient Greeks worked to perfect architectural form. They carefully calculated geometry and proportion to create buildings whose various elements blended together to form a unified whole.

The earliest Greek temples were probably built of wood. The Greeks then took the elements of those early wood structures and used them to create temples of stone masonry. Many of them still stand today. Greek temples were built with a simple construction system called post-and-lintel. In this type of construction, vertical columns (posts) support horizontal beams (lintels).

One of the most lasting developments of Greek architecture is the system of styles, or orders, used to build Greek temples. The orders, called Doric, Ionic, and Corinthian, are best identified by the tops, or capitals, of the columns. The Doric order had simple capitals and was the least decorated. Ionic capitals were more delicate and ornate, resembling scrolls. Corinthian capitals were the most decorative, featuring ornately carved acanthus leaves. Greek temples were built on these regular orders. But there was great variety in the temples, from the earliest to the latest. This reflects a spirit of experimentation within the system.

The Parthenon is a Doric temple. It is one of the best examples of Greek temple construction. Built between 447 and 432 B.C., it contained an enormous statue of the god Athena. Carved sculptures were located in the Parthenon's pediments (the triangular spaces at each end of the building, just beneath the roof) and friezes (decorative horizontal bands of continuous relief sculptures directly above the columns).

Every Greek city had an agora, the center of economic, political, social, and religious activity. Long covered walkways called stoas ran along two or more sides, housing small shops and stores.

The architecture of the ancient Romans blended local traditions with influences from other cultures, especially Greece. Until fairly recently, the Romans were thought to have merely copied Greek architecture. Today, however, ancient Rome's many contributions to architecture are considered as significant as those of any other culture.

The Romans were particularly skilled at building with bricks and stones. With these materials, they developed new roof forms using arches, vaults, and domes. To create an arch, wedge-shaped stones or bricks, called voussoirs, were placed with the narrow ends on the inside of the arch and the wide ends on the outside. The top or center voussoir was called the keystone. It held all the other voussoirs in place. The Romans typically used round or pointed arches to span openings in walls or to support heavy roofs.

Other forms of the arch developed by the Romans include the barrel vault. It is like a series of arches built next to one another to form a tunnel. The groin vault consists of two arches or barrel vaults that intersect at the top. A dome can be thought of as a series of arches built in a full circle around a center point.

Another important architectural development of the ancient Romans was the perfection of concrete. Roman concrete was a mixture of crushed or small stones, lime, water, and volcanic ash. It was as strong as stone. But it was cheaper to make and easier to work with. Concrete could be molded into forms such as vaults and domes. A famous example is the dome of the Pantheon, one of the largest Roman temples, built about A.D. 120. The dome has a diameter of 142 feet (43 meters). The Romans always covered concrete with small tiles of marble, brick, or other masonry materials.

The center of a Roman city was the forum, or public square. The typical forum had a small temple at one end and a courtyard flanked by colonnades. Also in a forum was a basilica. A basilica is a rectangular structure with semi-circular spaces called apses at each end. The central space had shorter side aisles and was lit by clerestory windows. Basilicas were used to hold crowds gathered for legal, social, or commercial activities.

The Romans were also talented engineers. The long, arched aqueducts that carried water into Roman cities from as far away as 50 miles (80 kilometers) still stand today.

The spread of Christianity throughout the Roman Empire beginning in the early 300's led to a need for new churches. Christian worship demanded a style of architecture very different from the religious architecture of Greece and Rome. The earlier temples had served as a house for the god, a storehouse for treasures, and as a background for outdoor ceremonies. Christians worshiped together inside their churches. So the plan of early Christian churches was based on Roman basilicas. These had plenty of open space and windows to let in light.

One of the earliest examples of Christian architecture was the old St. Peter's church in Rome, completed in 333. Colonnades divided the interior into three parts. There was a central nave (where the congregation gathered) and two aisles on either side. The altar stood in an apse at the far end of the nave. Underneath was the tomb of Saint Peter. With the addition of a cross-aisle (called a transept), the plan of the old St. Peter's looked like a crucifix—the symbol of the Christian church. This basic plan, with variations, can be seen in many Christian basilicas and cathedrals to this day.

Early Christian art and architecture influenced by Eastern traditions is called Byzantine, after the city of Byzantium (modern-day Istanbul). Byzantium became the capital of the Eastern Roman Empire in A.D. 330. At that time, it was renamed Constantinople by the emperor Constantine I.

Byzantine churches were round or in the form of a cross with arms of equal length (a shape known as a Greek cross). Such plans are described as centralized because they focus attention on the center of the space rather than the end.

One of the greatest examples of the Byzantine style is Hagia Sophia (Greek for "holy wisdom"). It was built in Constantinople between 532 and 537. The center of the church is a vast open space lined on each side by two-story colonnades. Towering 180 feet (55 meters) above the nave is a great dome about 100 feet (30 meters) in diameter and covered in gold mosaics. The dome was supported by pendentives. These are triangular braces with curved sides that rose from massive columns at each corner of the walls beneath. Half-domes flanked the great dome on two sides.

The Byzantine style of architecture spread to Greece, Russia, and finally through Venice to western Europe.

Islamic architecture developed about 650. It is best represented by mosques (where Muslims go to worship). Mosques are typically entered through a long court that opens into a large prayer hall. On one wall is an arched niche that indicates the direction of Mecca. Mecca is the holy city of Islam. The faithful are called to prayer from the minarets standing outside the mosque. Most mosques have one or more domes.

Like Christian basilicas, mosque designs varied according to local traditions. The mosque at Cordoba, Spain (late 700's), mixed Spanish and Islamic architectural customs. In the Middle East, mosques such as Masjid-i-Jami (early 1000's) in Iran were often decorated with colored, glazed tiles. The tiles were typically covered with scripture from the Koran and abstract geometric or floral designs (a style called Arabesque).

After the fall of Rome in A.D. 476, many construction techniques and architectural styles were lost. But by about the year 1000, there was a significant revival of architecture. The buildings built during the 1100's and 1200's have elements of the architectural forms of ancient Rome. So this style came to be called Romanesque. Romanesque buildings, however, appear more massive and stocky than the buildings of ancient Rome. They have thick walls, small windows, dark interiors, round arches, and short columns. And Romanesque buildings were made of stone instead of concrete.

The Romanesque cathedral was built on the typical basilica plan. But it was more complex than its Roman and early Christian ancestors. More altars were added along the side aisles and the apse. Decoratively carved arches were placed over doors. Towers often rose above each side of the entrance.

Romanesque architects experimented with vaults. They developed a new structural system called rib vaulting. It was first used in cathedrals in Caen, France (1068), and Durham, England (1100). Over square or rectangular sections of the nave, supporting ribs sprang from four corner columns and crossed like a groin vault at the ceiling's peak. This structural system made possible the lighter and taller vaults that would characterize Gothic cathedrals.

Buildings designed in the Gothic style, particularly cathedrals, appear to reach toward heaven. This effect is achieved by the combination of three building techniques. They are rib vaults, pointed arches, and flying buttresses.

Rib vaults helped create very steep, slanting roofs. Pointed arches over doors and windows stressed the vertical line of the building's design. Flying buttresses were arched braces that supported the walls of a building from the outside. The weight of the ceiling was transferred from the walls to the flying buttresses. That way, the walls could be made thinner. The vertical emphasis of a Gothic cathedral was further enhanced by tall, slender spires and extensive use of stained glass windows that filled the interiors with light.

Gothic architecture's roots are in Romanesque architecture. But it is generally considered to have originated with the work of a French abbot named Suger. In his design for a new choir in the apse of St. Denis (1144), Suger used rib vaults to open the space to the light coming through the stained glass windows. Flying buttresses were first used extensively on the nave of Notre Dame's cathedral (1163 to about 1250) in Paris.

The Renaissance (meaning "rebirth") began about 1400. It marked a deliberate break with the art and literature of the immediate past. The Italians, in particular, wanted to revive what they viewed as the greatness of ancient Rome and Greece. A new interest arose in the architectural styles of those cultures, which are commonly known as classical architecture.

The center of the early Renaissance was Florence. There, Filippo Brunelleschi designed what is commonly considered the first Renaissance building: the Ospedale degli Innocenti (Foundling Hospital) for orphans (1421). The front, or facade, of the building was composed of a row of wide arches, called an arcade, that rose above slender Corinthian columns. Brunelleschi's design for the Old Sacristy at the Church of San Lorenzo in Florence (1421-28) demonstrates the balance and proportion that Renaissance architects favored. The building was organized on geometric principles. It was a perfect cube topped with a half-circle dome. Brunelleschi used pendentives between the base and the dome.

In 1506, construction began on a new church to replace the old St. Peter's in Rome. The new St. Peter's Basilica became one of the greatest achievements of the Renaissance and one of the world's most famous buildings. Donato Bramante created the original plan for the building. He was followed by a series of talented Renaissance architects. Each modified the preceding designs. Michelangelo took over the project in 1546, and the church was completed on his design. His greatest contribution to the church was its magnificent dome.

The Renaissance arrived in France, Spain, and England in the late 1500's. But those nations never fully adopted the pure form of classicism achieved in Italy. In France, Renaissance forms borrowed from Italy were blended with the French Gothic tradition. In addition to churches and other religious structures, the Renaissance also shaped the design of palaces. This included Louis XIV's famous palace at Versailles, completed in 1685.

Baroque architecture developed between the late 1500's and the early 1700's in Italy, France, Austria, and other nations. Where Renaissance architecture expressed stability, baroque architecture gave the impression of movement. It did this through ornate and lively designs, contrasts of light and shadow, and curved shapes. Circles were replaced by ovals. Columns were doubled or twisted. Pediments were broken. And cornices (horizontal moldings that project over the edges of roofs) were curved. Giovanni Lorenzo Bernini best represented the baroque style in Rome with his designs for St. Peter's in 1656, particularly the two curving colonnades of the piazza, or square.

Beginning in the 1700's, there was another revival of interest in classical architecture. This movement, called neoclassicism ("new classicism"), developed out of two broad trends. The first trend was Palladianism. Palladianism was a revival of classical architecture through the study of the works of the Italian Renaissance architect Andrea Palladio. In 1715, Palladio's writings on architecture were first published in English. These books spurred architects in England to look to buildings such as Palladio's Villa Rotunda (1550-67) for inspiration. In 1725, Richard Boyle (Lord Burlington) designed a villa called Chiswick House, in Middlesex, England. It followed the Renaissance classicism of the Villa Rotunda.

The second trend that defined neoclassicism was the development of the field of archaeology. Beginning in the 1700's, scholars from England and France grew increasingly interested in studying the architecture of ancient Greece and Rome firsthand. The English architect Robert Adam developed a popular neoclassical style. It was based on his examinations of the archaeological ruins of ancient Rome. The interior of Adam's Syon House (1762-69), built in Middlesex, was inspired by the design of ancient Roman baths. The design of columns, friezes, and other elements in this house were influenced by Adam's careful study and measurement of ancient Roman decoration.

Neoclassicism coincided with the reign of the English kings George I-IV (1714-1830) in England. So in England, this style of architecture was referred to as Georgian. The popularity of Georgian, neoclassical architecture also coincided with the birth of the United States. And it defined the first significant architecture built in the new nation. Thomas Jefferson's design for his house, called Monticello, was influenced by Palladian neoclassicism. His design for the Virginia State Capitol (1785-96), with its simple rectangular form and front colonnade topped by a pediment, was directly inspired by an ancient Roman temple called the Maison Carrée (about 16 B.C.).

In most cases, neoclassicism did not result in pure revivals of classical styles. The United States Capitol building (completed 1863), for example, reveals the architectural influence of ancient Greece and Rome, as well as the Renaissance.

Modern architecture arose out of two important developments that occurred in the rapidly changing world of the 1800's. For the first time in centuries, new building materials were available. These included cast and wrought iron, steel, and reinforced concrete. And new kinds of buildings were needed to accommodate new ways of living and working. These building types included factories, railroad stations, and tall office buildings.

Toward the end of the 1800's, architects began to experiment with new materials. This can be seen in structures such as St. Pancras train station in London (1865) and the Eiffel Tower in Paris (1889). Both were built using wrought iron and were feats of engineering that showed the strength and potential of industrial materials. In 1892, French builder and engineer François Hennebique patented a system of embedding steel rods inside concrete columns and beams. Concrete that is reinforced in this manner is a relatively light yet very strong material. It can be used in a variety of ways.

With so many new methods, materials, and building types to choose from, architects debated which style was appropriate for the times. Some, such as those involved in a revival of the Gothic style, looked to the past. Others tried to create new styles, looking to nature and other sources for inspiration. This included architects associated with the movement called art nouveau ("new art").

The American architect Louis Sullivan was among the first to analyze the relationship between the design of a modern building and its use. He designed the Wainwright Building (1891) in St. Louis, Missouri. It utilizes his theory that tall office buildings should be designed in three parts. The base, or ground floor, of the building had large openings of glass to provide light for shopping and other commercial activities. The middle section consisted of numerous floors of offices, all exactly the same. The top level provided space for equipment to operate the building. This concept continues to influence skyscraper design today.

Most of the advances in engineering that occurred in the late 1800's and early 1900's took place in the United States. Many European architects praised American engineering. But they criticized the continued use of decoration on buildings. In 1908 an Austrian architect, Adolf Loos, wrote an influential essay in which he argued that architectural ornamentation of any kind was no longer needed in a modern, advanced society.

One American who captured the admiration of European architects was Frank Lloyd Wright. Working mainly in the Chicago area, Wright completely transformed the American house. The interiors of Wright's houses, which he called prairie houses, were open and spacious. Low-pitched roofs and deep overhanging eaves created long, low silhouettes that were in harmony with the flat midwestern landscape. Wright's revolutionary designs were admired by young German architects such as Walter Gropius. Gropius later founded Bauhaus, a famous school of modern design.

Another important German architect was Ludwig Mies van der Rohe. He designed the German pavilion at the 1929 International Exhibition, held in Barcelona, Spain. It was a one-story building about the size of a house. It showed how new materials could be used to create entirely new types of spaces. The pavilion had a light, steel structure that supported a flat roof. The interior spaces were defined not by traditional walls but by freestanding slabs of thin marble.

One of the most famous and influential of all modern architects was Charles Édouard Jeanneret, known as Le Corbusier. In 1929, Le Corbusier designed a house called the Villa Savoye, built outside Paris. The house was raised up on thin columns, called pilotis, so that it seems to hover over the ground. Inside, rooms were connected by a series of ramps that led to an outdoor terrace on the flat roof. Long, horizontal openings in the walls, called ribbon windows, lit the interior.

In 1931, the architectural designs of Walter Gropius, Mies van der Rohe, Le Corbusier, and others were showcased at an exhibition at the Museum of Modern Art in New York. The exhibition organizers noted that the new architecture was light rather than massive. It expressed its function clearly. And it did not rely on styles of the past. It was characterized by simple, geometric lines and the use of concrete, steel, and large areas of glass. They called this new architecture the international style.

After World War II (1939-45), the international style dominated modern architectural design around the world. This was especially true for office buildings. A typical example is Lever House (1950-52). Lever House was a skyscraper built in New York by the architectural firm of Skidmore, Owings, and Merrill. Lever House had a horizontal base elevated on pilotis. From that base rose a rectangular tower covered in a thin sheath of aluminum and glass. Soon similar towers defined the skylines of cities across the United States, Europe, and elsewhere. German architects such as Gropius and Mies van der Rohe, had emigrated to the United States. They became educators and trained an entire generation of young architects in the style. However, the influence of the international style was short-lived.

After the 1950's, architects began to explore new means of expression. Several architects expanded the use of reinforced concrete. Le Corbusier led the way with his design for the chapel Notre Dame du Haut (1955), in Ronchamp, France. It has a boldly curved roof made of a thin shell of reinforced concrete held together by concrete struts. A narrow strip of windows just below the roof makes it appear to float. Numerous other windows pierce the thick walls, filling the inside of the chapel with an otherworldly light.

American architect Louis Kahn also used concrete in his design for the Salk Institute in La Jolla, California. The design and materials lent themselves to the creation of both large open spaces for group research and quiet, private areas for individual study. The buildings were carefully designed to reflect the character of the site, with its dramatic ocean views.

Other architects used concrete to create bold, expressive forms. Frank Lloyd Wright designed the galleries of New York City's Guggenheim Museum (1959) as a series of ramps spiraling around a central atrium, or court. The TWA Terminal (1956-62) at Kennedy International Airport in New York was designed by Finnish architect Eero Saarinen. It features curved concrete shells that resemble a bird about to take flight.

An often overlooked but important influence on architecture after World War II was the growing movement to the suburbs. U.S. cities saw a tremendous loss in population as families moved to new housing developments in outlying areas. One of the first of these developments was Levittown, built on Long Island, New York, in 1948. Its designers adapted methods of mass production used in industry, enabling houses to be built quickly and cheaply.

In 1956, Southdale, the first fully enclosed, environmentally controlled shopping center, opened in a suburb of Minneapolis. Its architect, Victor Gruen, intended the center to be the new "town square" of the suburbs. It was to have places for people to socialize as well as shop. That same year, General Motors opened a complex of offices and research facilities in suburban Detroit, designed by Eero Saarinen. Soon other businesses were relocating to the suburbs.

During the 1960's, a group of architects emerged who were dissatisfied with what they viewed as the plain simplicity of the international style. The followers of this movement, which later became known as postmodernism, decorated their buildings with elements that recalled historical styles. The American architect Robert Venturi was an early leader of the movement. He thought architecture should reflect life by being complex and filled with contradictions. Michael Graves' design for the Portland (Oregon) Public Service Building (1983) featured historical elements. These included columns that were simulated (not structural) with colors and bas relief. Philip Johnson topped his design for AT&T's headquarters in New York City (1984) with a classical pediment. I. M. Pei's design for the new entrance to the Louvre in Paris (1989) featured a pyramid constructed of steel and glass.

Venturi and fellow architects Denise Scott Brown and Steven Izenour wrote a book called Learning from Las Vegas (1972). In it they suggested that architects should also look to commercial shopping centers and other common neighborhood features for inspiration. The book accompanied a growing interest in vernacular architecture.

Throughout the 1970's, many architects focused their attention on historic preservation and the architecture of the city. Projects such as the 1976 renovation of Quincy Market in Boston drew shoppers back into the city from the suburbs. They reminded people of the rich history and character of cities.

Most architects strive to make balanced structures that are in harmony with their surroundings. Other architects purposely seek to make their structures clash jarringly with their surroundings. This movement is called deconstructivism because the architects seem to deconstruct, or take apart, a conventional building and reassemble its various elements in an apparently random or jumbled fashion. In his design for the Wexner Center (1989) on the campus of Ohio State University, the American architect Peter Eisenman combined forms from buildings that had previously existed at the site with forms from the existing campus. This resulted in walls and other parts of the building intersecting one another at unexpected angles.

Buildings designed by the American architect Frank Gehry resemble deconstructivist architecture. But Gehry had a different method and purpose. He used computer modeling programs. That way he could calculate structural systems and create buildings in shapes that would have been impossible to achieve even 20 years earlier. Gehry's Guggenheim Museum (1997) in Bilbao, Spain, looks like an explosion of curving forms clad in a shiny skin of titanium.

Computer modeling programs have also made possible the structural feats of other designers. These include Richard Rogers, Norman Foster, and Santiago Calatrava. They designed bridges, train stations, airports, and exhibition halls with sweeping roofs supported by columns, trusses, or cables. Calatrava's addition to the Milwaukee Art Museum (2001) has a roof that looks like two great wings spreading out from the building. In fact, these wings actually move. Such buildings recall the great engineering feats of early modernism. And they point to a future of increasingly dynamic buildings, based on a new era of materials and structural techniques.

Architects design buildings. But they are not the only people involved in constructing them. They usually work with many related professionals, such as engineers, interior designers, landscape architects, and urban designers. Architects themselves must have broad knowledge of all these fields. Architects typically must earn a four-year undergraduate degree. Then they take a two- or three-year program of graduate study, leading to the Master of Architecture (M.Arch) degree. Once the architecture student graduates, he or she works as an intern to gain experience in all the different aspects of design and construction. After this period, the intern takes a registration exam. Only after passing this exam may the intern take the title and full responsibilities of an architect.

- from The New Book of Knowledge®