Mohenjo-daro is a remarkable construction, considering its antiquity. It has a planned layout based on a grid of streets, with structures constructed of bricks of baked mud and burned wood. At its height the city probably had around 35,000-40,000 residents. It had an advanced drainage system, a variety of buildings up to three stories high, and an elaborate bath area. Being an agricultural city, it also featured a large well, granary, and central marketplace. Perhaps most unexpected, it even had a building with an underground furnace (hypocaust), possibly for heated bathing.
The city was successively destroyed and rebuilt at least seven times. Flooding by the Indus is thought to have been the cause of destruction.