Mohenjo-daro

27.3242°N, 68.1389°E.

Mohenjo-daro in Sindh Province, Pakistan — one of the two principal urban centres of the Indus Valley Civilisation (the other being Harappa 600 kilometres north), occupied between approximately 2600 and 1900 BCE during the mature phase of the civilisation. Original urban area approximately 250 hectares with an estimated peak population of 40,000–80,000. The city was built on a precise grid plan with parallel streets oriented to the cardinal directions, multi-storey houses built of fired brick with internal courtyards, a sophisticated stormwater system with covered sewers serving every building, and a centralised Great Bath complex constructed with bitumen-sealed brick to hold water. The civilisation declined for reasons that remain disputed — climate change, river course changes, or invasion are all proposed — and the city was abandoned by approximately 1700 BCE. Excavated by R. D. Banerji in 1922 and continuously by Indian and Pakistani missions since. UNESCO World Heritage Site since 1980.

The largest city of a civilisation whose script has never been deciphered, with a sewage system more sophisticated than most cities of the world had through the medieval period.