Arunachala (IAST: Aruṇācalam [əɾʊˈɳaːtʃələ], 'Red Mountain') is a hill in Tiruvannamalai district, Tamil Nadu, and one of the five main Shaiva holy places in South India.

In order to settle the argument, Lord Shiva is said to have manifested as a column of light, and then the form of Arunachala.

Lord Shiva, in response to their request, bowed down to a mountain and a small torch appeared on top of it, and everyone worshiped.

The Maheswara Khanda of Skanda Purana, sage Veda Vyasa describes in great detail the wonder of Arunachala.

One should go round either in mouna (silence) or dhyana (meditation) or japa (repetition of Lord's name) or sankeertana (bhajan) and thereby think of God all the time.

"[13] Throughout the year, pilgrims engage in a practise called giri valam (circumambulation of Annamalaiyar temple and Annamalai hill 14 km in circumference), considered to be a simple and effective form of yoga.

[16] Every year, on the tenth day of the celebration of Karthikai, devotees take embers in pots from the sacred fire lit in the Arunachaleswara temple and carry them to the top of Arunachala, along with cloth wicks.

An enormous cauldron is placed on the highest of Arunachala's five peaks and filled with hundreds of gallons of ghee mixed with camphor.

At precisely six o'clock, as the sun sets and the full moon rises, lights are lit on the top of the Hill, on a flagstaff in the temple, and at Sri Ramanasramam, accompanied by chants of Arunachala Siva by the vast crowds.

In 2004 the Tiruvannamalai Greening Society was founded by district forest officer Pasupathy Raj and other local officials.

The Forest Way employs full-time and part-time staff and engages volunteers to grow seedlings of native trees and plant them on the mountain.