Mohenjo-Daro was an Indus Valley city constructed on a grid-plan and made of sunbaked brick, featuring extensive drainage and plumbing systems. There are records of private bathing areas, toilets, and hundreds of wells in the city—some of the earliest known in the ancient world. The Great Bath was a large, watertight pool built near a citadel and was thirty-nine feet long, twenty-three feet wide, and eight feet deep. The Great Baths likely served not only a recreational purpose, but also might have been a place for religious rituals.