Arulmigu Sri Agastheeswarar Temple is a revered Hindu temple in Agasthiyampalli, Nagapattinam district, Tamil Nadu, dedicated to Lord Shiva. The presiding deity, Agastheeswarar, is celebrated in the 7th-century Tamil Saiva work, Tevaram, composed by saint poets, the Nayanmars. Classified as Paadal Petra Sthalam, the temple is locally called Agasthiyar Kovil. The temple performs six daily rituals and hosts three annual festivals, including the Brahmotsavam, attracting thousands of devotees.
The town, Agasthiyanpalli, is named after the deity Agastheeswarar. Legend tells of the sage Agasthiyar, who moved south at Lord Shiva’s request to balance the earth’s tilt during Shiva and Parvati's marriage, witnessed by the assembled Devas in Kailash. It is believed that Shiva appeared to Agasthiyar in his marriage form here, which has established the temple's spiritual significance.
Inscriptions from the medieval Chola and later Pandya periods provide historical insights into Agasthiyanpalli and Agastheeswarar Temple. They mention grants to the temple during the reigns of Rajaraja Chola I, Rajendra Chola I, and Kulothunga Chola I, highlighting the temple’s significance in Chola-era Saivism. These records, along with inscriptions from nearby Vedaranyeswarar Temple, showcase the Chola dynasty’s devotion.
Following the Chola period, Agasthiyanpalli and the surrounding region experienced a power struggle between the Pandyas and Hoysalas. Despite this turbulence, royal patronage of the Agastheeswarar Temple persisted, with further contributions from the Nayak rulers. One inscription mentions Pandya king Kulasekaran, who, after recovering from an ailment through prayer, established a festival at the Vedaranyeswarar Temple to commemorate the occasion.