Thirumalai is also known as Arhatsugiri (Arihantgiri), located northwest of Polur, Tamilnadu. It is an important historical place for Jains. The hill has 140 steps. An 18 feet high idol of Bhagwan Neminath (known here as Shikha Maninath) is seen on the top of the hill. This idol is believed to be dated as old as the 12th century. It is believed that if one applies the holy water (gandhodak) many diseases could be cured. We can see various ancient caves existing in this Jain Math along with a 16 meter idol of Neminath.

Last ‘Shrutkevali’ Bhadrabahu and 8000 saints stayed at this place and did meditation, Swadhyay, etc. Very old caves still exist here. More than 100 Granth (Religious books), written on Tadpatra (Tree leaves) are available to be seen here. A Gurukul (Hostel school) is run by the Digambar Jain trust.

At the foot of the Thirumalai hill, there is separate sannidhi for Mahaveera. This seems to have been built during the Vijayanagara period in the 16th century. This temple was built to the west of the Kunthavai Jinalaya. There are paintings at the back of the main deity – which probably belongs to the Vijayanagara period – possibly later.

The temple has a three tier Rajagopuram and is surrounded by walls on all sides. It has a Panchaparameshti shrine near the entrance. A well called as Moondradi Kinaru, was used by the people in ancient times. The story of Shri Dharmadevi indicates that she had been used the well for feeding her children in her previous life.

Source:

http://en.encyclopediaofjainism.com/index.php/Khstra_Arihantgiri_(TN)

https://en.wikipedia.org/wiki/Arahanthgiri_Jain_Math

https://tamilnadu-favtourism.blogspot.com/2017/02/tirumalai-jain-complex-arani.html