The small town of Nabha, neighbouring Patiala, was once a princely state in its own right, and grew around the Qila Mubarak. Characterised by its soaring mud walls, the fort was constructed over a period of 150 years. Raja Hira Singh, who ruled from 1871 till his death in 1911, built most of the structure that stands today. The inner precinct is built on a square platform boasting colonnades, arches, and grand balconies. In 2010, the Qila Mubarak was leased to the Nabha Foundation.