When nature gives you a 2,300-foot stone spire, it's time to make a strategic lookout. At least that must have been the logic behind the ancient Kalavantin Durg.

Nothing more than a small cave built into the summit of a towering spike of rock, the fort, built around 530 BC, nonetheless gives a perfect view of the surrounding Indian lands. The fort is only accessible by ascending thousands of hand-carved steps, known as the "Climb to Heaven," which rise at a dizzyingly steep angle to the top of the spire. While no one is sure of the true origins of the fort or its name, tradition holds that the lookout was named after a princess, although there is no evidence to support this. The fort no longer holds any military significance, but it still attracts waves of foreign visitors each year who want to brave the treacherous steps up to the top.