The city was approximately one square mile in size. In 1922-1927 large scale excavations at Mohenjo-daro were carried out by R. D. Banarjee and continued by M. S. Vats and K. N. Dikshit under the direction of Sir John Marshall. E. J. H. MacKay carried out further excavations from 1927 to1931. Sir Mortimer Wheeler made small excavations in1950.
As a result of this extensive work almost one-third of the area of the old city was exposed, revealing for the first time the remains of one of the most ancient civilizations in the Indus Valley. Typical of most large and planned cities, Mohenjo-daro had planned city streets and buildings. The settlement was thought to house roughly 5,000 people, and had houses, a granary, baths, assembly halls and towers.
The city was divided into two parts, the Citadel included an elaborate tank or bath created with fine quality brickwork and drains; this was surrounded by a verandah. Also located here was a giant granary, a large residential structure, and at least two aisled assembly halls.
To the east of the citadel was the lower city, laid out in a grid pattern. The streets were straight, and were drained to keep the area sanitary. The people of the city used very little stone in their construction. They used two types of bricks- mud bricks, and wood bricks, which were created by burning wood. They used timber to create the flat roofs of their buildings; there are brick stairways leading to the roofs of many houses.
All Indus valley sites including Mohenjo-daro and Harappa, were built according to a grid pattern plan. Each city had broad parallel streets which crossed each other to divide the city into compact rectangular blocks, and had an advanced and extensive drainage system. In addition to its numerous other achievements Mohenjo-daro and other Indus sites made extensive use of baked brick (unlike the sun-dried brick typical of Mesopotamian civilization), which gave greater durability to all of its buildings.
Defensively Mohenjo-daro was a well fortified city. Though it did not have city walls it did have towers to the west of the main settlement, and defensive fortifications to the south. These fortifications taken into consideration, as well as a comparison to the Harappa ruins to the northeast, lead to the question of whether Mohenjo-daro was an administrative center.
Both Harappa and Mohenjo-daro share relatively the same architectural layout (Harappa is less well preserved due to early site defilement), and were generally not heavily fortified like 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, however the extent and functioning (and even the placement and type) of an administrative center remains relatively.
Soanian People ~500,000 (Soan Valley Civilization)
Mehrgarh Culture 7000–2800
Indus Valley Civilization 3300–1750 (Mohenjo_daro)
Vedic Civilization 2000–600
Indo-Greek Kingdom 250-10AD
Gandhara Civilization 200–1000AD (Harrappa, Sirkap)
Indo-Scythian Kingdom 200–400AD