We went on our first Arunachala Girivallam in Nov 2008. We were guided by Mr Anand who is the manager of Nannagaru Ashram. He took us through the path and showed us various darshans of Arunachala.
Near the point where the highway to Bangalore bridges off from the Girivallam road he showed us Arunachala and the three rock projections.
He told us that this is called as Trimurthi darshan by Sadhguru Sri Nannagaru. The three rock projections represent the three main gods Brahma, Vishnu and Shiva.
Any wish asked off the Hill will fructify from here.