Aadi Ratneswarar Temple is located at Tiruvaadaanai near Karaikkudi in Sivagangai District
. It is a vast temple dedicated to Lord Shiva
. The temple, with a nine-tiered 130 ft high Rajagopuram
is spread over an area of 10 acres. The principal deity is called Aadaanainathar. There are separate shrines for Goddess Anbayiammai, Surya
and Chandikeswarar. The temple houses several sculptures and mandapams which include the Chokkatanchari mandapam with 291 carved pillars, well-spaced prakarams and imposing walls. The main festival is the annual Brahmotsavam
celebrated in the month of Vaikasi (May-June). There is a separate festival for the Goddess in the month of Aadi (July-August). Arudra Darisanam and Kartikai Deepam are the other festivals conducted here.