Architecture: quotes, facts and reflections - Page 2

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WonderArchitecture

The Great Mosque of Kairouan in Tunisia, founded in 670 and largely rebuilt in 836, is one of the oldest mosques in the Islamic world. Its courtyard, columned prayer hall and square minaret became a model for mosques across North Africa.

The Arab general Uqba ibn Nafi chose the site when he founded the city of Kairouan in 670. The mosque was rebuilt several times, and most of what stands today dates from the reconstruction ordered by Emir Ziyadat Allah I in 836. Its prayer hall is hypostyle, meaning the roof rests on rows of columns: 414 of them, in marble, granite and porphyry, taken from ancient sites such as Carthage, so their shafts and capitals vary. The 31.5-metre minaret, rising in three stages from a square base, is thought to be the oldest minaret still standing. The mosque became a model for later mosques across the Maghreb, the part of North Africa west of Egypt, and is part of Kairouan's World Heritage Site.

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WonderArchitecture

Great Zimbabwe, the stone city built by ancestors of the Shona people between the 11th and 15th centuries, has huge granite walls laid without mortar. It was the capital of a kingdom that traded gold towards the Indian Ocean coast.

The ruins spread over several square kilometres in the south-east of today's Zimbabwe, and at its height the city was probably home to up to 10,000 people. Its best-known structure, the Great Enclosure, has walls up to 11 metres high, some topped with chevrons, a zigzag pattern of set stones. Excavations found Chinese pottery, glass beads, coins from Arabia and a coin minted at Kilwa on the Swahili coast, signs of the city's place in Indian Ocean trade. Colonial writers claimed Africans could not have built it. David Randall-MacIver in 1905 and Gertrude Caton-Thompson in 1929 showed it was the work of the Shona's ancestors, yet Rhodesia's government kept promoting other theories until independence in 1980. Dzimbabwe means houses of stone in Shona, and the country took its name from the city.

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WonderEngineering

The Shushtar Historical Hydraulic System in Iran is a network of dams, bridges, tunnels, canals and mills on the Karun River, much of it built in the 3rd century CE. It watered farmland, supplied the town and drove water mills.

Tradition traces the first canals at Shushtar to the Persian king Darius the Great in the 5th century BCE, but the system's key works belong to the Sasanian Empire. The Band-e Kaisar, or Caesar's Dam, a weir about 500 metres long across the Karun, is said to have been built by Roman soldiers captured when the Sasanian king Shapur I defeated the emperor Valerian in 260 CE. It raised the river so that water could be led into canals and rock-cut tunnels, where it drove mills and fed fields before pouring down a series of falls into a basin below the town. Thirteen dams, bridges and other works operated as one system. UNESCO listed it as a World Heritage Site in 2009.

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WonderEngineering

A hypocaust was the Roman system of underfloor heating: a furnace sent hot air under a floor raised on small pillars and, in some buildings, up through hollow walls. It warmed baths and wealthy homes.

The name comes from Greek words meaning 'heated from below'. Under the floor stood rows of small brick or stone pillars, called pilae, and a furnace outside the room pushed hot air and smoke into this low space; hollow box tiles set into the walls could carry the heat upwards and out. Roman writers credited a wealthy businessman of the early 1st century BCE, Sergius Orata, with inventing heated 'hanging baths', but historians doubt he was the first to warm floors this way. The architect Vitruvius described how to build such baths late in the 1st century BCE, and the system spread across the empire, from Britain to North Africa. Keeping it going took a steady supply of fuel and enslaved workers or servants to tend the fires.

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StillnessArchitecture

A mashrabiya is a projecting window enclosed by a carved wooden lattice, common in old Arab towns. The screen breaks up glare, lets breezes through and allows people inside to watch the street without being seen.

The earliest evidence of the mashrabiya in its present form comes from 12th-century Baghdad under the Abbasid caliphs. It spread to Egypt, the eastern Mediterranean, Arabia and beyond, reached its peak under the Ottomans, and goes by other names: shanashil in Iraq, rawashin in Jeddah. The lattice is usually finer at the bottom and more open at the top, so air moves fast above head height and gently lower down, and jars of water placed in the window cooled the breeze by evaporation as it passed over them. Privacy mattered too: the household could follow life in the street while staying out of sight. Mashrabiyas fell out of use in the 20th century, but architects now study them again as a way to cool buildings without machines.

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WonderArchitecture

Muqarnas is a form of Islamic architectural decoration made of tiers of small niches, stacked like a honeycomb. It bridges the corners where a square room meets a round dome, and crowns doorways and vaults.

Western writers have often called muqarnas 'stalactite' or 'honeycomb' vaulting. The earliest surviving examples are simple three-part corner niches beneath domes, such as those in the Arab-Ata Mausoleum at Tim in Uzbekistan (977–978) and the Gonbad-e Qabus tower in Iran (1006–1007). The oldest complete muqarnas dome known to modern scholars crowned the Imam Dur Mausoleum at Samarra in Iraq, finished in 1090. Historians still debate whether the technique began in north-eastern Iran or in Abbasid Iraq. Built of brick and plaster, carved stone or wood, it spread across the Islamic world: Seljuk builders in Anatolia set it over great stone gateways, and in Spain it fills the ceilings of the Alhambra.

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WonderDesign

Girih tiles are a set of five shapes that medieval Islamic craftsmen used to plan the interlaced star-and-line patterns on walls and domes. Some of their 15th-century patterns come close to a kind of order mathematicians only described in the 1970s.

Girih is Persian for 'knot'. Each of the five tiles, a decagon, a pentagon, an elongated hexagon, a bowtie and a rhombus, carries decorative lines. Laid edge to edge, the lines join into continuous bands, so a maker could build a vast design from a few pieces. In 2007 the physicists Peter Lu and Paul Steinhardt showed that some patterns, notably on the Darb-i Imam shrine in Isfahan (1453), come close to quasicrystalline order: an arrangement that is highly regular yet never repeats itself exactly, like the Penrose tilings that mathematicians described in the 1970s. The craftsmen reached it through geometry and practice, centuries before anyone had the mathematics to describe it.

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WonderArchaeology

Nan Madol, off the island of Pohnpei in Micronesia, is a ruined city of basalt walls, tombs and ceremonial buildings on roughly a hundred artificial islets divided by tidal channels.

Islet-building began by the 8th or 9th century, and the great basalt walls went up from about 1180–1200. The site became the ceremonial and political seat of the Saudeleur dynasty, which ruled a united Pohnpei until about 1628; rival chiefs were made to live there, where they could be watched. The builders used long, naturally many-sided columns of basalt, quarried elsewhere on Pohnpei and brought to the site, stacking them in alternating crosswise and lengthwise courses around platforms filled with coral rubble. How they moved and raised such heavy stone is not recorded. The mortuary sector, Madol Powe, includes the walled royal tomb islet of Nandauwas. UNESCO listed Nan Madol in 2016 and placed it at once on its List of World Heritage in Danger, as silt and mangroves were choking the channels.

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WonderTrade

Kilwa Kisiwani, an island off the coast of Tanzania, was one of the richest Swahili trading cities from the 13th to the 15th century. It controlled the gold trade of the southern coast and built its mosques and palaces of coral stone.

The Swahili were Muslim African trading communities of the East African coast. Kilwa grew rich when its sultans took control of the gold trade at Sofala, in today's Mozambique, where gold from the Zimbabwe plateau reached the sea. Merchants brought cloth, glass beads and porcelain from Arabia, Persia, India and China. The Great Mosque, one of the oldest standing on the coast, and the vast Husuni Kubwa palace were built of coral stone. For some 500 years Kilwa minted its own coins, mostly copper, which have been found as far inland as Great Zimbabwe. A Portuguese fleet sacked the city in 1505 and its trade declined. UNESCO listed the ruins in 1981; they were on its danger list from 2004 until conservation work allowed their removal in 2014.

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DriveEngineering

Prestressed concrete has steel cables stretched tight inside it, so the concrete is already squeezed before any load arrives. Concrete cracks easily when pulled but is very strong when squeezed, so this lets beams and bridges span farther.

In ordinary reinforced concrete, loose steel bars carry the pulling forces, but the concrete around them still cracks as it bends. Prestressing goes further. In pre-tensioning, steel strands are stretched before the concrete is poured and released once it has hardened; in post-tensioning, cables run through ducts in hardened concrete and are then pulled tight and anchored. Either way, when traffic or weight later tries to stretch the underside of a beam, it first has to cancel that built-in squeeze. The French engineer Eugène Freyssinet patented a practical method in 1928, using high-strength steel so that the squeeze would not fade over time. From the mid-20th century prestressing became standard for bridges, car parks and floor slabs, allowing longer spans and thinner sections.

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WonderEngineering

Weathering steel, often known by the trade name Cor-Ten, is an alloy that forms a tight, stable layer of rust when it is left out in the weather. That layer slows further corrosion, so the steel needs no paint.

Ordinary rust flakes off and exposes fresh metal, so corrosion keeps eating inward. Weathering steels contain small amounts of copper, chromium, nickel and phosphorus, which help the rust form a dense layer, called a patina, that sticks to the surface and keeps out much of the oxygen and moisture. Its colour darkens from orange to deep brown over a few years. US Steel introduced the alloy in 1933 for railway wagons carrying coal and ore. It only works where the surface can dry out between wettings; constant damp, sea salt or water trapped in joints defeats it. The first building to leave it bare was the John Deere headquarters in Moline, Illinois, designed by Eero Saarinen and completed in 1964.

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WonderEngineering

Near the top of Taipei 101 hangs a 660-tonne steel sphere that swings against the tower's sway in strong wind, so people inside feel much less movement. Engineers call this device a tuned mass damper.

Taipei 101, a 508-metre skyscraper in Taiwan's capital, opened in 2004. Its gold-painted sphere is 5.5 metres across and hangs from the 92nd down to the 88th floor, where visitors can see it. The ball is tuned to the tower's own natural rhythm of swaying but moves out of step with it, so each push of the wind is partly cancelled, while hydraulic dampers turn the motion into heat. It can reduce the building's movement by up to 40 per cent. During Typhoon Soudelor in August 2015 the ball swung a record one metre. Smaller tuned dampers steady bridges, chimneys and power lines; London's Millennium Bridge was fitted with them after it wobbled under crowds when it opened in 2000.

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DriveEngineering

Some buildings in earthquake zones do not sit directly on their foundations but on flexible bearings made of rubber and steel. When the ground shakes, the bearings take up most of the movement and the building above sways far more gently. Engineers call this seismic base isolation.

A conventional building is tied rigidly to the ground, so it takes on almost every jolt. In an isolated building, bearings separate the structure from its foundation. They are usually stacked layers of rubber and steel, often with a lead core that soaks up energy; the lead-rubber bearing was invented in New Zealand by Bill Robinson in 1974. Because the building shifts slowly on its bearings, upper floors feel much weaker shaking and equipment inside is more likely to keep working. The building needs a gap around it so that it can move, and its pipes and cables need flexible joints. San Francisco City Hall, Wellington's Te Papa museum and, in Istanbul, the Sabiha Gökçen Airport terminal and Başakşehir Çam and Sakura City Hospital all stand on isolators.

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WonderArchitecture

Caravanserais were fortified roadside inns built along trade routes across the Middle East, Anatolia and Central Asia. Behind one strong gate, merchants found rooms, storerooms, stables and water, and because the inns stood about a day's journey apart, caravans could plan each stage.

The word comes from Persian: kârvân, a caravan, and sarây, a palace or large building. A typical caravanserai was a courtyard ringed by rooms, with animals and goods kept safely inside the walls at night. Rulers and wealthy patrons built them to encourage trade, and many were supported by charitable foundations. In Anatolia the Seljuks built a dense network in the thirteenth century; the Sultan Han on the Konya–Aksaray road, built in 1229, is one of the largest. In Iran, the Safavid ruler Shah Abbas I added many more around 1600, and in 2023 UNESCO listed 54 Persian caravanserais as World Heritage. Besides shelter, they were places to trade, exchange money and hear the news from other cities.

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WonderHistory

Ise Grand Shrine, the holiest site of Shinto, Japan's native religion, takes down its main sanctuaries every 20 years and rebuilds them exactly on the plot next door. The custom began in 690 and, despite some long interruptions, continues today; the next rebuilding is due in 2033.

The rebuilding is called Shikinen Sengū. Along with the buildings, the shrine's furnishings and sacred objects are made anew, and the wooden Uji Bridge at the entrance is rebuilt too. The timber is hinoki, a Japanese cypress. Power tools are not allowed within the shrine grounds, so the work falls to miyadaiku, carpenters trained in traditional shrine building; less experienced carpenters usually learn on the bridge before they work on the sanctuaries. Shinto calls the idea tokowaka, 'ever young': renewing a sacred building keeps it fresh and passes the skills from one generation to the next. The present buildings, from 2013, are the 62nd set. Wars have delayed the cycle more than once, most notably for over a century during Japan's civil wars of the 15th and 16th centuries.

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