The walled city of Shibam is one of the most extraordinary urban sights in the world: a tight grid of mud-brick towers, five to eleven storeys tall, packed inside a rectangular defensive wall on the flat floor of the Wadi Hadramawt. UNESCO inscribed it as a World Heritage Site in 1982. Most of the houses date from the sixteenth century onward — earlier buildings have washed away in periodic floods — but the city itself is far older, mentioned as the seat of the Hadrami sultanate in the second century and probably occupied since pre-Islamic times.
Walk in through the south gate, the only original entrance, and the streets immediately narrow into shaded canyons of mud brick. The towers are not detached buildings but a single continuous wall of construction; party walls are shared, and in places you can see how the upper floors of one house were grafted onto its neighbour. The ground floors are for animals and storage, the middle floors for daily life, and the top floor — the mafraj — is the high-windowed reception room where the men of the family would gather to chew qat in the afternoons. Look up for the white gypsum bands around the windows, freshly repainted every few years to reflect heat, and for the carved palm-wood doors at street level. Maintenance is constant: a mud-brick city in a flash-flood valley does not stand by accident.