Mohenjo Daro Flourishing around 2000 B.C.E., Mohenjo Daro was by far the largest city of the Indus Valley civilization, covering more than 600 acres. This photograph shows a small part of that city as it has been uncovered by archeologists during the past century. The large water-tight tank or pool, shown in the foreground, probably offered bathers an opportunity for ritual purification. (J. Mark Kenoyer/Harappa Images)