Neelayathachi Amman Temple is situated in the heart of Nagapattinam. This 1000-year-old Shiva temple is also known as Sivarajathaani Aathipuranar Parppathirsaram Karonamoorthy. Kayarogana Nathar or Kayarogana Moorthy and Karunthadankanni alias Arulmigu Neelayathachiamman are the presiding deities. There are also idols of Nagaparana pillaiyar, Mavadi Pillaiyar and Kulathankarai Pillaiyar.
Six pujas are performed daily. Theppam, car procession, aadi pooram amman peengan ratham urchavam are conducted.