Thursday, October 2, 2008
Surrounded by a 23-foot-high (7-meter) mud-brick wall, the Yemeni city of Shibam lies at the southern edge of the Rub’al-Khali Desert at the junction of several wadis and the Hadramawt Valley. Popularly known as the “Manhattan of the Desert,” this city of about 7,000 inhabitants has more than 500 earthen high-rise houses, up to twelve stories high—the world’s oldest skyscrapers—neatly contained in a quarter-square-mile (half a square kilometer) rectangle. The city has been there for at least 1,800 years, but most of these remarkable dwellings date from the sixteenth century. Inscribed on UNESCO’s World Heritage List in 1982, Shibam was described as “one of the oldest and best examples of urban planning based on the principle of vertical construction.”
Shibam was on the caravan route of the incense trade and replaced Shabwa as the capital of the Hadramawt in the third century a.d. Since then, it has enjoyed several periods of religious, political, and especially commercial power. Because it stands on a hillock barely 100 feet (30 meters) above the floor of the deep Hadramawt wadi, Shibam has been victim to floods, and it was partly destroyed by water in 1532. Thus flood protection is among the reasons given for the traditional form of its unique high-rise houses; others include the need to conserve agricultural land (the city is surrounded by groves of date palms), the desire to gather patriarchal families under one roof, and, more pragmatically, at least in earlier times, to accept the protection afforded by the perimeter wall.
Many of the towers of sun-dried, straw-reinforced mud brick taper upward, perhaps to ensure greater stability. The external walls, up to 130 feet (40 meters) high, are partly load bearing. They are set on stone foundations, supported by a framework of timber posts and beams and a large internal stairway built of stone. At ground-floor level the walls are from 4 to 6 feet (1.3 to 2 meters) thick. Interior surfaces are finished with a skim coat of lime plaster to which egg whites are added, producing a highly polished surface. The exteriors are stuccoed with a mixture of clay and chopped straw. High above the narrow lanes that separate the buildings, the living quarters on the upper floors are joined by networks of covered flyovers, so that neighbors can meet without needing to climb up and down stairs. The uppermost floors are usually covered with a thick layer of impermeable white stucco that not only protects from the rain but also reflects much of the solar radiation.
Ventilation is an important constraint upon the design in the relentless desert heat. The crowding of the tall buildings within such a small urban area produces some degree of self-shading. The walls are pierced by regular rows of narrow windows, rooms often having upper and lower sets that from outside create an illusion of more stories than there really are. Openings are closed with wooden mashrabiyas and doors, some as much as 800 years old, elaborately carved with open geometric patterns to encourage natural ventilation. The highest row of openings allows hot air to flow from the interior of the building in the summer.
Some inhabitants of Shibam have been forsaking these traditional houses for modern dwellings that line the highway to Suyan, about 30 miles (19 kilometers) away, producing a version of urban sprawl. Without maintenance, the skyscrapers in this “Manhattan of the Desert” are deteriorating; many are cracking and showing symptoms of collapse. Indeed, over the last decade, more than thirty have succumbed to the elements. Despite UNESCO’s listing and the self-conscious effort of the local people—rigorously applied building codes insist upon traditional designs, materials, and techniques—to conserve its character, the unique architectural landscape of Shibam is in imminent danger of disappearing.