The unique Indus Valley city of Dholavira, located in Gujarat, is internationally famous for which unique architectural feature?
Dholavira, located on Khadir Bet island in Rann of Kutch, is divided into three distinct parts (Citadel, Middle Town, and Lower Town) and possesses a phenomenal, highly advanced system of rain water harvesting reservoirs. [Memory Trick: High 'Dhola' (drums) collect sweet 'Vira' (water) in grand reservoirs.]