A mastaba (/ˈmæstəbə/, /ˈmɑːstɑːbɑː/ or /mɑːˈstɑːbɑː/) or "pr-djt" (meaning "house for eternity" or "eternal house" in Ancient Egyptian), is a type of ancient Egyptian tomb in the form of a flat-roofed, rectangular structure with inward sloping sides, constructed out of mud-bricks (from the Nile River) or stone. These edifices marked the burial sites of many eminent Egyptians during Egypt's Early Dynastic Period and Old Kingdom. In the Old Kingdom epoch, local kings began to be buried in pyramids instead of in mastabas, although non-royal use of mastabas continued for over a thousand years.