Situated in a mountain valley at an altitude of 2,200 m, the Old City of Sana'a is defined by an extraordinary density of rammed earth and burnt brick towers rising several stories above stone-built ground floors, strikingly decorated with geometric patterns of fired bricks and white gypsum. The ochre of the buildings blends into the bistre-colored earth of the nearby mountains. Within the city, minarets pierce the skyline and spacious green bustans (gardens) are scattered between the densely packed houses, mosques, bath buildings and caravanserais