Nannilam is located near Thiruvarur. This is one of the Mada Temples built by Chola king Kochenganan.
The temple is praised by Saint Sundarar in his Thevaram hymns. This is the 71st Lord Shiva Temple on the southern bank of Cauvery praised in hymns.
Lord Shiva in the temple is a swayambulingamurthy.
It is believed that those bathing in the sacred spring in Masi Month-February-March and worship the Lord will gain all benefits in life and those worshipping on Ekadasi days-11th day of full moon or new moon days and pradosha days-13th day in both fortnights will reach Moksha-salvation.