A mastaba is a type of ancient Egyptian tomb in the form of a flat-roofed, rectangular structure with inward sloping sides, constructed out of mudbricks or stone. The term mastaba comes from the Arabic word for "a bench of mud". Historians speculate that the Egyptians may have borrowed architectural ideas from Mesopotamia, since at the time they were both building similar structures.

The above-ground structure of a mastaba is rectangular in shape with inward-sloping sides and a flat roof. The exterior building materials were initially bricks made of the sun-dried mud readily available from the Nile River. Even after more durable materials such as stone came into use, all but the most important monumental structures were built from mudbricks. Mastabas were often about four times as long as they were wide, and many rose to at least 30 feet in height.

Mastabas evolved over the early dynastic period. During the 1st Dynasty, a mastaba was constructed simulating house plans of several rooms, a central one containing the sarcophagus and others surrounding it to receive the abundant funerary offerings. The whole was built in a shallow pit above which a brick superstructure covering a broad area. Old Kingdom mastabas were used chiefly for nonroyal burials. In nonroyal tombs, a chapel was provided that included a formal tablet or stela on which the deceased was shown seated at a table of offerings.

Egyptologists use the Arabic word mastaba, meaning bench, for the massive rectangular structures found above many tombs in Saqqara, Gizeh, and other places. They often have rooms for offerings inside which are decorated with reliefs or paintings. In the Old Kingdom, they had a separated room serdab in which one or more statues of the tomb owner and his family were placed. The earliest mastabas are found at Tarkhan, Saqqara, and Gizeh.

In summary, a mastaba is a rectangular tomb found in Ancient Egypt, built of mud brick or stone, with sloping walls and a flat roof. It was used chiefly for nonroyal burials and had a chapel provided that included a formal tablet or stela on which the deceased was shown seated at a table of offerings.