Head to Salimgarh Fort and learn about its role in defending against attacks and invasions. This structure has witnessed some interesting history in its time.
You'll have no end of sightseeing choices when staying in Old Delhi. Salimgarh Fort is a great place to start here, but there are plenty of other interesting places to consider. Swaminarayan Akshardham Temple, Red Fort, and India Gate are close to the history-filled fortress and will fill in your day nicely.