GENERAL KNOWLEDGE

Detailed explanation-1: -Some of the oldest known structures which have served as citadels were built by the Indus Valley civilisation, where citadels represented a centralised authority. Citadels in Indus Valley were almost 12 meters tall. The purpose of these structures, however, remains debated.

Detailed explanation-2: -The cities in Harappa were divided into two parts-one part smaller and raised above the ground called the citadel, and the other bigger called the lower-town. The bigger area situated below the citadel was called the lower town. It had all the residential buildings and public facilities.

Detailed explanation-3: -a fortress that commands a city and is used in the control of the inhabitants and in defense during attack or siege. any strongly fortified place; stronghold.