Apatsahayesvarar Temple, Alangudi or Guru Sthalam or Tiru Irum Poolai is a Hindu temple dedicated to Lord Shiva located in the village of Alangudi in the Valangaiman taluk of Tiruvarur district, Tamil Nadu, India. Shiva is worshipped as Apathsahyesvarar, and is represented by the lingam. His consort Parvati is depicted as Elavarkuzhali. The presiding deity is revered in the 7th century Tamil Saiva canonical work, the Tevaram, written by Tamil saint poets known as the Nayanmars and classified as Paadal Petra Sthalam. The temple complex covers two acres and it houses a five tier gateway tower known as gopurams, one facing the Apathsaheswarar shrine and other towards North. The temple has a number of shrines, with those of Apathsaheswarar and his consort Elavarkuzhali being the most prominent. The temple has six daily rituals at various times from 6:00 a.m. to 8:30 p.m., and four yearly festivals on its calendar. The Brahmotsavam festival celebrated during Chittirai (April–May) is the most prominent festival. The original complex is believed to have been built by Cholas, while the present masonry structure was built during the Nayak during the 16th century. In modern times, the temple is maintained and administered by the Hindu Religious and Charitable Endowments Department of the Government of Tamil Nadu.