Rudratheertham

The place was already sacred owing to the presence of Lord Paramashiva. He was worshiping Lord Maha Vishnu under the waters of the 'Rudratheertham' (the sacred pond near the temple).

Later, Lord Shiva emerged out of the waters when the Prachethas, son of King Pracheenabarhis came in search of a place to worship Lord Maha Vishnu. He then revealed the hymn 'Rudra Geetha' to Prachethas And then the Prachethas worshiped Lord Maha Vishnu for another ten thousand years staying in the 'Rudratheertham' After the installation of the idol of Mahavishnu by Guru and Vayu, Lord Shiva moved to the nearby Mammiyoor temple

http://wikimapia.org/143268/Guruvayur-Rudratheertham

http://www.astrojyoti.com/rudragita.htm
Gem
http://godivinity.org/rudra-gitam-a-hidden-gem/
Download
http://bhagavatam.co.uk/Rudra-Gita.php
Scripture
http://www.indianscriptures.com/vedic-knowledge/sacred-scriptures/gita/rudra-gita
Base
http://vedabase.net/sb/4/30/en2