Mohenjodaro, a planned city

Mohenjodaro is the best-known Harappan city, and it was clearly planned. It had two parts:

• the Citadel: small but high, built on a raised platform, and walled;
• the Lower Town: much larger and lower, also walled, where most people lived.

Platforms were built first, and the buildings came later, on top of them. Raising the Lower Town's platforms alone would have taken about four million person-days of labour: a sign of strong organisation.

Bricks had a standard ratio of length, breadth and height, 4:2:1, in every Harappan settlement, whether sun-dried or baked.

Streets ran in a grid, crossing at right angles. Drains were built first, with houses along them; every house was connected to the street drains, and the drains had sumps for cleaning.

Houses were built around a courtyard. There were no windows in the ground-floor walls facing the street, for privacy. Many houses had their own well, and a bathing area. On the Citadel stood special buildings: the Great Bath, a large tank made watertight with bricks set on edge and gypsum mortar, and a big warehouse.

Plan first, build later.