Most Andorran houses are made of stone. Since the flat land is used for farm crops, the rural houses are frequently backed against the mountainsides. The high villages (cortals) are situated on a line between the highest fields and the lowest limits of high-level pastures. Isolated houses (bordes) are found at higher elevations. Many families maintain temporary dwellings in the highest pasture areas. All residents have access to safe water and sanitation systems.