3700 Vaishnavites

Sibi Chakravarthi stayed there with his warriors, a white boar crossed his path. He chased it and the boar hid inside a hole. Markandeya, a sage, was doing penance there and the king narrated the incident to him. The sage asked the king to fill the hole with milk. While doing so, Hindu god Vishnu appeared before them. The sage asked the king to bring 3700 Vaishnavites from the north and build a temple on the site for Vishnu. As requested, the king took 3700 Vaishnavites and started building the temple. While doing so, one of the Vaishnavites was killed in transit and the king was concerned by the accident. Vishnu appeared incognito as Pundarikakshan, a Vaishnavite, and requested to be counted among the 3700.

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Origin of Name 

Tiruvellarai is the avathara sthalam for two prominent acharyas, Uyakkondaar and Engalalvan. Uyakkondaar, know intially as Pundarikakshan was one of the two sishyas of Nathamuni, Kurukai Kavalappar is the other. When Nathamuni wanted to wanted to train each the path for moksha, Pundarikakshar took the path of Divya Prabhandam, which has the potential to provide mokasham for the entire human race. Pundarikakshar was able to help the entire world by learning the prabhandas from Nathamuni and making sure that the recitation and the text are preserved for future acharya and bhaktas. Hence Nathamuni, named him Uyakkondar, for his selfless service to others. 

59 Steps 
The moolavar who is on top of the hill has to be approached by climbing 59 steps. 

1. The first 18 of these are said to represent the 18 chapters of Bhagavad Gita. 
2. The next 4 steps represent the four vedas. After crossing these, one reaches the Bali peetam. After offering prayer at Bali peetam, 
3. one has to cross 5 more steps, which represent the Pancha boothams. After which we find the affromentioned Naazhi kEtta Vaasal. Then one goes around the hill in a pradakshina form, crossing two entrnaces viz., Utharayana and Dakshinayana. 
4. After crossing these entrances, there are eight setps representing the Ashtaakshara Mantram. 
5. Then comes the final 24 steps that represent the Gayatri Mantram. 

http://en.wikipedia.org/wiki/Sri_Pundarikashan_Perumal_Temple