This is one of the most important Vishnu temples in Kerala. Worshipping the Lord here is considered to be as beneficial as worshipping at the Guruvayoor temple. Legend says that Vilwamangalath Swamiyar was performing puja at Guruvayoor and in the frenzy of devotion hit the idol of the Lord with the back of his hand. The Lord was displeased at the carelessness of Swamiyar and disappeared telling him to look for him at Ananthankadu. Swamiyar was distraught at what had happened and walked in search of his beloved Lord. When he reached Thammanam in Ernakulam he saw the footprints of more the Lord with the markings of the conch, discuss, maze and lotus and consecrated Him there. Originally the area was under the local chieftains called the Anchikaimal. Eight Nair families of the place took the initiative in constructing the temple. Pallana Panikkar, one of the leaders, took the name of Ananthapuram Panikkar. Other families like Aaryaveedu, Vyloppilly and Cherupilly at Kaloor, Cheruparambath at Thekkumthala, Manthanadu at Vyttila who were among those who cooperated in the construction still live in these areas. It is believed that Swamiyar left Thammanam after the construction of the temple and reached Thiruvananthapuram where he saw the lord and consecrated him as Ananthashayana Moorthy. The temple is under the Cochin Devaswom board now.