In Tamil language "Giri" means mountain and "valam" means circumambulation. On full Moon Days and festival days like Karthigai Deepam, Tamil New year day hundred of thousands of devottees walk around the mountain and worship Arunachala Temple of Tiruvannamalai and get the blessings of the Lord Arunachala and this is called Girivalam.
Here shiva has maifiested himself in the form of the Hill, it is considered auspicious to go around the hill by walk.
The length of girivalam road encircling the mountain is 14 Kms (81/2 Miles). During the Girivalam circling people worship Eight Siva Lingams (Astalingams) located around the Arunachala Mountain.
The best time for Girivalam is early morning 4.00 AM to 6.00AM (Bramha Muguratham)
The book Arunachala Mahatmayam says (Books about Tiruvannamalai and Girivalam)
"When one take one step for Girivalam, Indira becomeshis servent".
"When he takes two steps, kubera becomes hi servent, Vishnu becomes his servent"
During the Girivalam circling, people worship Eight Siva Lingams located around the Arunachala Moutain. Each lingam represent one direction. The eight lingams are by name
1.Indra Lingam (Guardian God of the East)
It is first of astalingam. Located Near Main Temple, in the car street.
2. Agni Lingam (Guardian God of the South East)
3.Yama Lingam ( Guardian God Lord of the South)
4. Niruthi Lingam (Guardian God of the South West)
5. Varuna Lingam, (Guardian God of the West)
6. Vayu Lingam, (Guardian God of the North West)
7.Kubera Lingam (Guardian God of the North)
8. Esanya Lingam. (Guardian God of North East)