Sigiriya is a spectacular formation in central Sri Lanka. It has been inhabited since pre-historic times, but,  most prominently ,it has been used as a fortress, a palace, and a monastery. The top of the rock still features the remnants of a 1500 year old sprawling palace, some of the beautiful frescos can still be seen on the side of the rock, and climbing the 1200 odd steps is well worth the trouble.