There are many theories and stories on the name (Thanthondri). It is believed that this hillock has formed itself as a (Suyambu) and some others say that it was found by the most adherent devotees of the Lord. There was a king named (Thaamaan Thondrikon) who ruled over this region with his residence at this hillock. This is evident from the legendary poem (Puranaanuru) (Puranaanuru 399:30-34). A few say that this place would have been named after him.
Once in Thirupatrkadal, Lord Thirumal (Lord Vishnu) was conversing with his Lord Thirumagal (Lord Lakshmi). At that time Adhisheshan (God of Snakes) was guarding the entrance. At that time the Vayubaghavan (God of Wind) wanted to seek the blessings of the Lord. Adhisheshan did not permit Vayubhagavan to see Lord Thirumal. There started a debate between them on who is the strongest and the powerful. At that time, Lord Thirumal came out and wanted to solve the problem. So he gave them a task to accomplish. The task is Lord Adhiseshan should hold Thiruvenkatamalai (Venkatachalam) with his body. The task of Vayudevan is to use all its power to take the hill out of the clutches of Adhisheshan. Adhisheshan held the hill firmly. But Vayubhagavan could not succeed in his attempt. So he was furious. He used all his power and transformed into a great cyclone and that broke the hill and it was thrown into pieces in all directions. One such piece is the hillock of Thanthondrimalai. This hillock has got the holiness of the Thiruvenkadamalai. All other pieces that were thrown out would also possess this holiness. Only because of this, this temple is called as the (Then Thirupathi).
Once upon a time, there was an Archagar who performed the pujas regularly. Once his relative passed away and he sent his son who was a small boy to perform the puja. There is a custom that the Lord is decorated with the life size garland (Nilai malai). On that day a devotee came there with the Nilai malai. That small boy is so short that he could not decorate the Lord with that garland. So he cried and prayed the Lord to bend a little (Venkataramana Devudu, please bend a little). Lord Perumal also bent for his convenience. Then the Archagas son happily decorated the Lord with the garland. Thus Lord Perumal has always lends his ears to the prayers offered by his devotees. Only because of this the number of devotees has been improving day by day
In general, temples in Tamil Nadu will be facing the Eastern direction. But this Thanthondriperumal Temple is facing the west. The hillock Thanthondri is spread from East to West. The western part of the hillock is elevated that the eastern part. This west facing temple is a cave temple. The Sanctum Sanctorum when the daily Perumal is presented is in the eastern part of the (Artha Mandapam). Only the Sanctum Sanctorum is the cave. (Artha Mandabam and the entrance hall were constructed later. There is a big stage with two pillars in the Sanctum Sanctorum. Three sides of the stage were deepened. In the eastern part of the stage along with the rock, Arulmigu Kalyanavenkataramana Perumal poses with Goddess Lakshmi in His Chest facing the western direction. Lord Perumal who stands and blesses the devotees with four hands has been praised as (Bhaktha Pratheenan).
The Vaishnavite temple is situated in a half a furlong hillock facing the eastern direction. This hillock is shaped as higher in the western direction and a bit lower in the eastern direction. The tower of this temple is on the top of this temple above the sanctum sanctorum which is located in a cave.
On the top of this hillock in a beautiful Kudavarai (cave) is the Lord Venkataramana swamy facing west in the standing position and offers his blessings to the swarming devotees. Here, Lord Perumal poses with Lord Lakshmi in his chest gigantically and there is no separate temple for the Thayar here.