legend behind the celebrations goes like this- Once upon a time the Devas, the heavenly immortals, put in their best possible efforts to have a complete Darshan of Lord Shiva. During this process Lord Brahma took the form of a swan and Lord Vishnu in the form of a boar conducted an extensive search in the sky and in the neither world did they find him Lord Shiva asked Lord Brahma and Lord Vishnu to find out the exact location of his head and his feet. Since Lord Shiva took a gigantic form, they were not able to find him anywhere. Then Lord Shiva appeared before them in the form of a flaming light whose ends cannot be defined on the hill of Thiruvannamalai. Therefore, this festival is also known as Annamalai Deepam. Here, a special torch is lighted on the zenith of the hill and it is believed that Lord Shiva's Jyoti will be visible on this day. The festival is celebrated in a special manner in Thiruvannamalai.