The Kasivishuwanathar Temple is located at Thenkasi. It is at a distance of 8 km from Courtallam. in 1455 AD the temple was constructed by the then ruler of the region, Parakkirama Pandian. According to legends, the king wanted to visit Kasi, but could not enter the city as the place was under the rule of Muslim Kings. So the king decided to build a replica of the original temple located in Kasi at his own town.
The chief deity here is Kasi Viswanathar. The temple tower with a height of 178 feet is a highlight of the temple. The Masi Magam festival that lasts for 10 days, Aipasi Wedding festival, Navarathri, Margazhi Thiruvadhirai and Karthikai Rudra Deepam are some of the major festivals celebrated here.