Apatsahayeshwarar Temple of Alangudi is located in Thiruvarur District of Tamil Nadu. This temple is about 18km from the temple-town of Kumbakonam. It is said to be auspicious to visit this Kshetra before Jupiter transits from one zodiac sign to another. ‘Alam’ in Tamil means poison. Shiva consumed the poison that was produced by the snake Vasuki during the Great Churn, giving rise to the name Alamgudi or ‘Alangudi’. Hence the presiding deity here is known as Apatsahayeshwarar as he saved everyone from the poison. He is also called Aranyeshwarar.

This is regarded as a ‘Gurustalam’ (Abode of Jupiter) where Lord Dakshinamurthy is held in great reverence. Sages Shuka, Viswamithra, Agastya, Adi Shankara are believed to have worshipped this Swayambhu Lingam here.