Adi Annamalai is the oldest temple around Arunachala. It was built hundreds of years before Arunachaleswarar Temple, which per Wikipedia, “The earliest known record of the temple is in the works of the poet Nakkirar of the third Tamil Sangam period. At that time, the temple might have been a simple wooden structure. The present masonry structure and gopurams (temple towers) date back approximately 1200 years.
“The name of this Temple, Adi Annamalai means ‘first’ or ‘ancient’ Annamalai (Arunachaleshwarar). Its size is small and it occupies only 1/2 acre in size – compared with the 25-26 acre size of Arunachaleswarar Temple on the Tiruvannamalai side of the Hill. The legend of Adi Annamalai recounts that Brahma, after His dispute with Vishnu about the fiery column, made a lingam and went to the other side of the Hill to worship Shiva. Thus, this lingam is supposed to be the first, ancient and original lingam of Annamalai and hence the name Adi Annamalai.”
Turning off the Hill Round Road (Girivalam Road), going through the small village of Adi Annamalai, you come to the temple, with its tower visible from far away.