Tomb of Khentkawes||
House boats and the Nile||
In short, mastabas were rectangular buildings often without any exterior decorations. Inside there was everything from one to many rooms. They were covered with wall-decorations that the gods about the person or the people buried in the mastaba. The actual burial ground could often be underground.
Mastabas are interesting because their interiors have so much more decorations and colours than the austere pyramids. In this respect they resemble the tombs of Luxor.
Giza's mastaba are often neglected by visitors and travellers' guide books alike. Of course Giza is famous for its pyramids, but do notice that if the mastabas had been located elsewhere it would have been a popular tourist destination by itself.
Inside the Mastaba of Neferbauptah.