Sri Sathyagirinatha Perumal Temple

Historians generally date the temple's excavation to the late 7th or early 8th century CE, making it one of the earliest surviving structures among the 108 Divya Desams. One scholarly assessment (art historian M.A. Dhaky) places the work in the 860s CE, comparing its sculptural style to the nearby Vijayalaya Choleeswaram at Narthamalai; an alternative view traces its rock-cut technique to earlier Pallava-period workmanship, following the same cave-temple tradition seen at the Mahabalipuram monuments further north. Either dating places it among the oldest physical structures anywhere on the Divya Desam list.

An 8th-century inscription found at the site records a renovation under the Mutharaiyar king Sattan Maran, whose mother Perumbidugu Perundevi gifted tax-free land for the temple's upkeep, direct epigraphic evidence, rare among the smaller Divya Desams, of the site's continuous royal patronage across more than one dynasty.

The temple later came under the patronage of the Pandyas, credited with granite additions in the 9th century CE, and subsequently fell within the territory of the Sethupathi rulers of Ramnad. In 1687 CE, Vijaya Raghunatha Sethupathi built a 40-acre fort around the hill, which still stands today and encloses the cave temple within its walls, meaning the shrine's later history is bound up with a distinct chapter of local military architecture rather than temple building alone.

Thirumayam's temple is architecturally distinct from almost every other Divya Desam: rather than a built gopuram-and-sanctum complex, it is a Kudavarai Kovil, a cave excavated into solid rock, in the same broad tradition as the Pallava monuments at Mahabalipuram. Carved in high relief across the rear wall of the cave is a monumental 22-foot reclining Vishnu (Anantasayana) sculpture, cut directly from the living rock, one of the most expansive such reliefs found anywhere in South Indian rock-cut temple architecture, and a striking companion to the standing form in which Perumal is worshipped here today. The site now sits within the grounds of Thirumayam Fort, the 1687 CE Sethupathi fortification, meaning a visit combines a Divya Desam with one of the region's significant historical military monuments.

The temple's car (ther) festival, held on the new-moon day of the Tamil month of Vaikasi (May/June), is among its most visible annual events, drawing crowds for the temple car procession around the streets adjoining the fort. The ten-day Aadi Poora festival in the following month of Aadi is another major observance, and the temple's calendar also includes Vaikasi Poornima, Krishna Jayanthi, Deepavali and Pongal, celebrated with the customary rituals of the Pandya Nadu Divya Desams.

Daily worship follows the customary morning and evening schedule of the region's Divya Desams; the car festival and Aadi Poora period see an expanded ritual calendar and considerably larger crowds than an ordinary day.