Thirumukkoodal has an ancient temple for Lord Vishnu called ‘Sri Appan Prasanna Venkatesa Perumal’Thirumukkoodal got its name as three rivers Palar (Ksheera Nadhi), Vegavathi (Saraswathi) and Cheyyar (Bahu Nadhi) merge together at this place. This place is called Triveni Sangamam and is considered equivalent to Ganges. Taking bath here is considered as holy as bathing in Prayag. The temple is beautifully located on the banks of the river giving a scenic view. The compound of the temple is just on the shore of the river is a wonderful site to see. Sri Lakshmi Narasimhar temple is located in Pazhaya Seevaram (pic below) on one side of the river and Sri Appan Prasanna Venkatesa Perumal temple on the other bank of the river.This temple is said to be 1200 years old, as the oldest inscription found in this temple belongs to 9th Century. This temple is said to have built by a king ruling Thondai Mandalam (with capital as Kanchipuram), by name Raja Thondaimaan Chakravarthy. According to the legend, the king Thondaimaan once started to Thirupathi to have dharshan of Lord Venkatesa Perumal. He then heard a divine voice telling him that it was not the time to visit Thirupathi as a king from a neighbouring country was nearing his kingdom to wage a war. The voice advised him to be with his son during war time to save the country and later to visit Thirupathi.On hearing this Thondaiman prayed to Lord Venkatesa Perumal and the Lord blessed him to win the battle and gifted him with His Sanku (Conch) and Chakra (Wheel). Thondaiman successfully won the battle and on his way back both the weapons Sanku and Chakra vanished. Later, the Lord directed Sri Ramanujar to install Sanku & Chakra for Him at this place.