El Ateuf, Algeria

Some 370 mi (600 km) south of Algiers, beyond the peaks of the Saharan Atlas, pink-rendered cities with narrow covered alleys sit in the soft light along Wadi M’Zab, which twists and turns through the plateaus along the Grand Erg Occidental, a sea of sand. The climate is harsh, hot and windy, and rain extremely rare. But these cities, established by the Mozabite people in the eleventh century, are marvels which have always astonished the great architects—Le Corbusier, André Ravereau, Frank Lloyd Wright. Extraordinarily cohesive, the cities of Wadi M’Zab are all built on a slope to escape rare but violent floods, and adhere to the same plan: homes are clustered around the mosque, which is at the city’s highest point, ramparts below. Palm groves provide fruits and vegetables and relief from waves of intense heat. Houses are organized around a main room, whose roof opens to a large square over the central patio where the family gathers. A staircase leads to the terrace, which is sometimes surrounded by small rooms in which the inhabitants sleep in winter.