Question

what is citadel of harappa​

Answer 1

Citadels in Indus Valley were almost 12 meters tall. The purpose of these structures, however, remains debated. Though the structures found in the ruins of Mohenjo-daro were walled, it is far from clear that these structures were defensive against enemy attacks. Rather, they may have been built to divert flood waters.

Answer 2

In Harappa. … plan to Mohenjo-daro, with a citadel resting on a raised area on the western flank of the town and a grid-plan layout of workers' quarters on the eastern flank. The citadel was fortified by a tall mud-brick rampart that had rectangular salients, or bastions, placed at frequent intervals.