Sultan Alla-Ud Din Bahman of the Bahmanid Dynasty shifted his capital from Gulbarga to Bidar in 1427 and built his fort along with a number of monuments in it. The fort was captured by Bijapur Sultanate in 1619–20, but fell to the Mughals in 1657; as a part of a Peace treaty.
The fort has five gates, 37 bastions and is surrounded by multiple moats. It houses multiple monuments, of which Rangin Mahal is the most decorated of them all. [Link]