The Pueblo peoples of the south-western United States have occupied their semi-arid homeland since – in their own words – “time immemorial”. The archaeological record and an abundance of architectural remains certainly afford credence to a very long period of occupation, dating back at least to the 10th century. The ruins of Chaco Canyon reveal a high level of social organization. This settlement, which was abandoned by 1299, still shows a remarkable built response to the environment.Both the historical remains and modern buildings are characterized by the use of locally available materials, including stone, adobe and wooden beams. The structures are typically low, although they can also be multi-storey; and they are almost always square or rectangular on plan with flat, earthen roofs. (Edward E. Crocker)