Ghadames, known as `the pearl of the desert`, stands in an oasis. It is one of the oldest pre-Saharan cities and an outstanding example of a traditional settlement. Its domestic architecture is characterized by a vertical division of functions: the ground floor used to store supplies, then another floor for the family, overhanging covered alleys that create what is almost an underground network of passageways and, at the top, open-air terraces reserved for the women.