Best to enter from the back gate. Arunachaleshwara Temple is a large compound surrounded by a wall. It has 4 gopurams (gateway towers) and many temples inside. It is a colorful magic place with hundreds of statues. The temple is dedicated to Shiva in his manifestation as fire. The main shrine that contains the Agni Lingam is not open to non-hindu visitors. You can join the queue for the shrine and wait the dark cave like temple, but when you approach the Lingam the priest will usher you past the statue so that you cannot see it. So it's better not to enter the queue, because the waiting can turn into a claustrophobic experience.
It's best to enter the temple from the back gate, i.e. the gate closest to the area of Ramana Ashram. Approaching from the front gate you will be molested by hundreds of beggars.
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