From the WHC Inscription:
The oldest constructions do not appear to be earlier than the 17th century, although their structure and technique were propagated from a very early period in the valleys of southern Morocco. The site was also one of the many trading posts on the commercial route linking ancient Sudan to Marrakesh by the Dra Valley and the Tizi-n’Telouet Pass. Architecturally, the living quarters form a compact grouping, closed and suspended. The community areas of the ksar include a mosque, a public square, grain threshing areas outside the ramparts, a fortification and a loft at the top of the village, an caravanserai, two cemeteries (Muslim and Jewish) and the Sanctuary of the Saint Sidi Ali or Amer.
The Ksar of Ait- Ben-Haddou is a perfect synthesis of earthen architecture of the pre-Saharan regions of Morocco.
Read More at http://whc.unesco.org/en/list/444