The Indus Valley Civilization developed around cities along the Indus River valley between 3300-1300 BCE. Two major cities were Mohenjo-Daro and Harappa, which had sophisticated urban planning with standardized bricks, buildings, roads, sewage systems, and an advanced drainage system. Mohenjo-Daro, one of the largest cities, was divided into the citadel area for public buildings and the lower city for homes. The civilization declined around 1300 BCE due to unknown reasons like flooding or invasion.