Salimgarh fort is built in triangular shape. Rubble masonry is used to construct the walls and circular bastions can be found on top of the walls.
Salimgarh Fort is connected to the red fort through an arch bridge which was built by Bahadur Shah Zafar. The gate between both the forts was named as Bahadur Shah Zafar Gate. Brick masonry and red sandstone was used to construct the gate. British built a railway line by demolishing the bridge which divided both the forts.
Aurungzeb converted the fort into a prison and made his brother Murad Baksh as prisoner. He also imprisoned his eldest daughter Zebunnisa as she became a poetess and wrote poems on the orthodoxy of the emperor. Bahadur Shah Zafar was also a prisoner and the British kept him here. Later he was shifted to Rangoon.
British also imprisoned the members of Indian National Army from 1945 till 1947. After independence the fort was renamed as Swatantrata Senani Smarak to commemorate the prisoners who fought for independence and died in the prison.
Tourists can visit the Swatantrata Senani museum which was the prison where many soldiers of INA died during British period. Colonel Gurubaksh Singh Dhillon chose the place for museum. In 2007, ASI wanted to shift the museum in order to provide better lightening, new galleries, and displays for other structures.