Salimgarh Fort was built in 1546 by Salim Shah Suri, son of Sher Shah Suri, on what was then a small island in the Yamuna River. It predates the Red Fort by a century and served as a prison for Mughal princes and later political detainees under British rule. Today it is connected to the Red Fort complex and can be visited on the same ticket.
The battlements and bastions afford excellent views of the Yamuna flood plain and the Red Fort walls. A small museum inside covers the history of prisoners held here, including Bahadur Shah Zafar's sons. It is less crowded than the Red Fort itself, making it a quieter place to absorb the layered history of Old Delhi.