Since 2011, UNESCO has classified the territory of the Causses and Cévennes on the World Heritage List as representative of mixed farming. The area extends over 1,158 square miles (3,000 km²) from the south of the Massif Central to the gateway of the Mediterranean. UNESCO also designated several gateway cities like Mende, in the Lozère department, for its cultural richness and its relationship with agriculture and livestock. Until the 19th century, the town traded woolen sheets from the Causses surrounding it and hosted many sheep and cattle fairs and markets. Mende's houses with roofs of Tournel schist slates were built from local limestone, tuff, or timber framing.