(Photo: Rohit Gowaika)
Prabalgad Fort, also known as Kalavantin Durg, is an old and now unused fort in the Western Ghats mountain range in the Indian state of Maharashtra. As you can see in this photo, the summit is small. But if properly supplied and fortified, any encampment there would be almost impossible to capture.
The origins of Prabalgad Fort are unknown, but it was occupied by at least 1458 and was in active military use by as late as 1826. The only way to the top is through a long staircase carved into the mountain. Tourists sometimes brave the climb, which is risky because there are no guardrails.