Architecture through the ages

Every building is a solution to the same problem: keeping a roof up and walls standing while resisting gravity, wind and time. The available materials and engineering knowledge of each era set the limits of what architects could build, and new techniques repeatedly transformed what buildings looked like.

Architecture also expresses power, belief and identity. Temples, palaces, cathedrals and skyscrapers were built to impress as much as to shelter.

The simplest structural system is post and lintel: two uprights with a horizontal beam across them. Stonehenge uses it, and so did Egyptian temples. Because stone beams crack under their own weight if they are too long, such buildings need many closely spaced columns.

Greek temples refined this system into an art. Their three main orders are recognisable by their columns: the plain Doric, as in the Parthenon in Athens; the Ionic, with scroll-shaped capitals; and the ornate Corinthian, decorated with acanthus leaves. Architects even curved the lines of the Parthenon subtly so it would look straight to the eye.

Roman engineers made great use of the round arch, which directs weight outward and downward, allowing wider openings than a lintel. Extended arches formed vaults, and rotated arches formed domes. Romans also developed a strong concrete. The Pantheon in Rome, completed around 125 CE, still has the world's largest unreinforced concrete dome.

Later builders developed these ideas further. The Hagia Sophia in Constantinople, completed in 537, raised a vast dome over a square space using curved supports called pendentives. Islamic architects built soaring domes, pointed arches and intricate geometric decoration, from the Great Mosque of Córdoba to the Taj Mahal.

• Pointed arches directed weight more steeply downward than round arches, allowing greater height.
• Ribbed vaults concentrated the roof's weight onto specific points instead of entire walls.
• Flying buttresses, external arched supports, carried outward thrust away from the walls.
• With walls no longer bearing all the load, builders filled them with huge stained-glass windows.
• Cathedrals such as Notre-Dame de Paris and Chartres took decades or even centuries to complete.

Renaissance architects revived classical symmetry, proportion and columns. Filippo Brunelleschi's dome for Florence Cathedral, completed in 1436, used an ingenious double shell and herringbone brickwork to be built without a full wooden support frame. Baroque architecture added curves, drama and grand urban spaces, as at St Peter's Square in Rome.

The Industrial Revolution brought iron, glass and later steel. London's Crystal Palace of 1851 was assembled from prefabricated iron and glass panels, and the Eiffel Tower of 1889 showed the height possible with iron. Steel frames and safe passenger elevators made the skyscraper possible, beginning in Chicago in the 1880s.

Modernist architects of the twentieth century rejected ornament in favour of function, clean lines and new materials. Le Corbusier promoted buildings raised on columns with open plans and long windows, and Ludwig Mies van der Rohe summed up the style as less is more. Frank Lloyd Wright pursued organic architecture in harmony with its setting.

Later architects reacted in turn. Postmodernists brought back colour, historical references and humour, while computer-aided design allowed the flowing forms of buildings such as Frank Gehry's Guggenheim Museum in Bilbao and Zaha Hadid's works. Today sustainability is a central concern, with architects designing for energy efficiency, natural ventilation and lower-carbon materials such as engineered timber.