Mohenjo-daro's architectural leap lies not in a single grand building but in an invisible system that orders the whole city: the plan. Where the Egyptian pyramids and the Ziggurat of Ur exalt the monument, the Indus cities organise ordinary life through infrastructure.

The city is divided into blocks by right-angled main streets running roughly north–south and east–west; this is not a village that simply grew but a pre-conceived grid. Bricks are produced to a standard ratio (about 1:2:4) — a shared unit of measure across the region, a building norm. The most striking feature is the drainage: nearly every house has a bathing area and a well, and used water leaves the house into covered brick channels along the streets, then into the city's main drains. Managing waste water through a public network is the moment architecture moves from the scale of the building to the scale of the city.

In the raised 'citadel' the Great Bath is a ceremonial pool made watertight with a layer of bitumen between double brick walls — showing that water management was not only technical but also ritual. There is little or nothing monumental in the way of palace or temple; the Indus may have expressed power not in a single structure but in a seemingly egalitarian urban fabric. Mohenjo-daro is the first large known application of the idea of the 'designed city' — grid plan, standard material, public infrastructure.