Ernakulam is the largest town of Kerala and is at present part of Cochin town which was the capital of Cochin kings before 1947. In the middle of the town is the Durbar hall ground and in its middle is the great temple of Ernakulathappan (The Lord of Ernakulam) . It is one of the very important temples of the former Cochin state dedicated to Lord Shiva.
The legend of this temple is also connected with Arjuna of Mahabaratha. Needing Pasupathasthra to win over Kauravas, Arjuna went to the forest to pray lord Shiva. He made a Shiva Linga with mud and started worshipping it . At the culmination of his great penance , Lords Shiva and Goddess Parvathi appeared before him and granted him his wish. Ernakulathappan is supposed to be that Linga which was worshipped by Arjuna. Forest completely surrounded the Linga and centauries later it was found by a sage called Devala , who due to a curse has been turned in to a snake. While moving about in the forest he happened to find this Linga and started worshipping it and regained his normal form. Devala was called as Rishi Nagam (Sage serpent) and had made a pond for use in worshipping the lord. This pond is called Rishi Naga Kulam. This temple has found place in the ancient Tamil literature as one of the temple maintained by Cheras.
In the year 1842 , Diwan Edukunni Sankara Warrier got the dilapidated temple rebuilt in the present form and was opened for worship in the year 1846. The presiding deity of the temple is Gauri Shankara in the form of a Lingam. This is supposed to Swayambu which means self made and not by man. On the northern side of the sanctum sanctorum is the temple of Kiratha Murthy (Which was worshipped by Arjuna) and on the southern side is a small Ganesa temnple. A small area behind the sanctum sanctorum is considered as the place where Goddess Parvathi lives and the eastern gate is known as Devi gate.Outside the Inner temple circle, shrines for Lord Ayyappa and Nagaraja also exist.