This 800m-high extinct volcano dominates Tiruvannamalai – and local conceptions of the element of fire, which supposedly finds its sacred abode in Arunachala’s heart. Devout barefoot pilgrims, especially on full-moon and festival days, make the 14km (four-hour) circumambulation of the mountain, stopping at eight famous linga. The inner path was closed at research time, but it's possible to circle around on the main road, or climb the hill past two caves where Sri Ramana Maharshi lived and meditated (1899–1922).
The hot ascent to the top opens up superb views of Tiruvannamalai, and takes five or six hours round-trip: start early and take water. An unsigned path across the road from the northwest corner of the Arunachaleshwar Temple leads the way up past homes and the two caves, Virupaksha (about 20 minutes up) and Skandasramam (30 minutes). Women are advised not to hike alone.
If you aren't that devoted, buy a Giripradakshina map (₹15) from the bookshop at Sri Ramana Ashram, hire a bicycle on the roadside opposite (per hour/day ₹10/40) and ride around. Or make an autorickshaw circuit for about ₹300 (up to double at busy times).