UNESCO: The Sassi and the Park of the Rupestrian Churches of Matera

The Sassi di Matera are two districts (Sasso Caveoso and Sasso Barisano) of the Italian city of Matera, Basilicata, well-known for their ancient cave dwellings inhabited since the Paleolithic period. The "Sassi" have been described by Fodor's as "one of the most unique landscapes in Europe".

Along with the park of the Rupestrian Churches, it was awarded World Heritage Site status by UNESCO since 1993. The Sassi are houses dug into the calcarenitic rock itself, which is characteristic of Basilicata and Apulia, locally called "tufo" although it is not volcanic tuff or tufa. The streets in some parts of the Sassi often run on top of other houses. The ancient town grew up on one slope of the ravine created by a river that is now a small stream. The ravine is known locally as "la Gravina".

Wikipedia