in Mohenjo-daro's construction , showing the surrounding urban layout Mohenjo-daro has a
planned layout with
rectilinear buildings arranged on a
grid plan. Most were built of fired and mortared
brick; some incorporated sun-dried
mud-brick and wooden superstructures. The covered area of Mohenjo-daro is estimated at 300
hectares. The
Oxford Handbook of Cities in World History offers a "weak" estimate of a peak population of around 40,000. The sheer size of the city, and its provision of public buildings and facilities, suggests a high level of social organisation. The city is divided into two parts, the so-called Citadel and the Lower City. The Citadela mud-brick mound around highis known to have supported public baths, a large residential structure designed to house about 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 more prestigious 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. Some buildings had two stories.
Major buildings In 1950,
Sir Mortimer Wheeler identified one large building in Mohenjo-daro as a "Great
Granary". Certain wall-divisions in its massive wooden superstructure appeared to be grain storage-bays, complete with air-ducts to dry the grain. According to Wheeler, carts would have brought grain from the countryside and unloaded them directly into the bays. However,
Jonathan Mark Kenoyer noted the complete lack of evidence for grain at the "granary", which, he argued, might therefore be better termed a "Great Hall" of uncertain function. Close to the "Great Granary" is a large and elaborate
public bath, sometimes called the
Great Bath. From a
colonnaded courtyard, steps lead down to the brick-built pool, which was waterproofed by a lining of
bitumen. The pool measures long, wide and deep. It may have been used for religious purification. Other large buildings include a "Pillared Hall", thought to be an
assembly hall of some kind, and the so-called "College Hall", a complex of buildings comprising 78 rooms, thought to have been a priestly residence.
Fortifications (left), which it seems were continually built up as flooding and rebuilding raised the elevation of street level Archaeologists have identified the foundations of eroded mud-brick walls that surrounded Mohenjo-daro. It was also fortified with guard towers to the west of the main settlement, and defensive fortifications to the south. Based on these fortifications and the structure of other major
Indus Valley cities such as
Harappa, scholars have postulated that Mohenjo-daro was an administrative center. Harappa and Mohenjo-daro share a similar architectural layout and were generally not as heavily fortified as other Indus Valley sites. It is obvious from the identical city layouts of all Indus sites that there was some kind of political or administrative centrality, but the extent and functioning of an administrative center remains unclear.
Water supply and wells The location of Mohenjo-daro was built in a relatively short period of time, with the water supply system and wells being some of the first planned constructions. With the excavations done so far, over 700 wells are present at Mohenjo-daro, alongside drainage and bathing systems. This number is unheard of when compared to other civilisations at the time, such as Egypt or Mesopotamia, and the quantity of wells transcribes as one well for every three houses. Because of the large number of wells, it is believed that the inhabitants relied solely on annual rainfall, as well as the Indus River's course remaining close to the site, alongside the wells providing water for long periods of time in the case of the city coming under siege. Due to the period in which these wells were built and used, it is likely that the circular brick well design used at this and many other Harappan sites are an invention that should be credited to the Indus civilisation, as there is no existing evidence of this design from Mesopotamia or Egypt at this time, and even later. Sewage and waste water for buildings at the site were disposed of via a centralized drainage system that ran alongside the site's streets. These drains that ran alongside the road were effective at allowing most human waste and sewage to be disposed of as the drains most likely took the waste toward the Indus River.
Flooding and rebuilding The city also had large platforms perhaps intended as defense against flooding. According to a theory first advanced by Wheeler, the city could have been flooded and silted over, perhaps six times, and later rebuilt in the same location. Some archaeologists believed that the site was abandoned after a final flood engulfed the city in a sea of mud.
Gregory Possehl was the first to theorize that the floods were caused by overuse and expansion upon the land, and that the mud flood was not the reason the site was abandoned. == Notable artefacts ==