The Sassi of Matera are two districts of Matera, the Sasso Caveoso and the Sasso Barisano, formed by rock buildings built in the natural quarries of the Materan Murgia and inhabited since the Paleolithic. Since 1993 they have been declared a UNESCO World Heritage Site. Together with the Civita district (built on the spur that separates the two Sassi), they form the historic center of the city of Matera. The "Sassi" have been described by Fodor as "one of the most unique landscapes in Europe".