Mohenjo-daro has a planned layout based on a street grid of rectilinear buildings. Most were built of fired and mortared brick; some incorporated sun-dried mud-brick and wooden superstructures. The sheer size of the city, and its provision of public buildings and facilities, suggests a high level of social organization. At its peak of development, Mohenjo-daro could have housed around 35,000 resid
ents. The city is divided into two parts, the so-called Citadel and the Lower City. The Citadel – a mud-brick mound around 12 metres (39 ft) high – is known to have supported public baths, a large residential structure designed to house 5,000 citizens, and two large assembly halls. The city had a central marketplace, with a large central well. Individual households or groups of households obtained their water from smaller wells. Waste water was channeled to covered drains that lined the major streets. Some houses, presumably those of wealthier inhabitants, include rooms that appear to have been set aside for bathing, and one building had an underground furnace (known as a hypocaust), possibly for heated bathing. Most houses had inner courtyards, with doors that opened onto side-lanes.
