Built by Ahmed Nizam Shah in 1490, this fort is a circular-shaped fort, which features 18 m high walls, supported by 22 bastions. One of the most well-designed and impregnable forts of India, the Ahmednagar Fort is currently under the control of the Indian military. Oval in shape, the fort's defensive system comprises 24 citadels and a moat that is 30 m wide and 4-6 metres deep. There are two entrances to the fort, which can be reached only after one goes over the moat, through the suspension drawn bridges. After countless invasions, the Ahmednagar Fort has taken many blows and come out relatively unscathed. The control over the Ahmednagar Fort had changed hands many times over, starting from the time of Mughal rule. The detailed history of the Ahmednagar Fort reveals that it had been used as a royal prison a number of times. Amongst the most important imprisonments, one that stood out was the time when the entire Congress Working Committee was detained at the Ahmednagar Fort during the Quit India Movement of 1942. Presently, some rooms in the fort have been converted into a museum. One can see the Leaders room, where Nehru and the other national leaders were imprisoned and where India's first prime minister, Pandit Jawaharlal Nehru, wrote his book, The Discovery of India, while being detained within the confines of the fort.