Kanheri Caves

More than a hundred Buddhist caves cut into a single basalt hill inside Sanjay Gandhi National Park. It is the largest such cluster on one hill in India, worked between the 1st century BCE and the 10th century CE as a monastic university. The great chaitya, or prayer hall, keeps its colonnade of carved pillars and its standing Buddhas, while channels and cisterns across the rock show how the monks stored monsoon rain. Open roughly 7:30 to 17:00, closed Mondays; park entry plus a small ASI fee, higher for foreigners. Go early.

A 2,000-year-old rock-cut monastery hidden inside the city's own national park