Kasi Viswanathar Temple is a Hindu temple dedicated to Lord Shiva located in Kumbakonam, Tamil Nadu, India. The temple is incarnated by the hymns of thevaram and is classified as Paadal Petra Sthalam.
This place has been referred to in thevaram written by Saint Poet (7th Century AD) Thirugnana Sambanthar and Thirunavukkarasar.This temple is referred back to Ramayanam period when Lord Rama and Lakshmana are said to have worshipped Shiva here during their search for Sita, and acquired Rudramsam, to enable them to fight Ravana. Legend has it that the nine sacred rivers of India, prayed to Shiva at Banares (Viswanathar) to be absolved of the sins washed away by bathers, and were directed to bathe in the Mahamagam tank and worship Adi Kumbeswarar Temple. Viswanathar of Kaasi is believed to have manifested himself here at Kumbhakonam at Kudandaikkaronam.
The temple has a nava kanniyar aka nava kannigais (Nine rivers) in the form of deities worshipping Lord Shiva and hence the temple is referred as 'Nava Kanniyar' temple. The lingam worshipped by Lord Rama is located in the north eastern prakaram (outer courtyard) of the temple. The lingam is believed to grow with time.