Sri Neelamegha Perumal Temple (with Manikundram & Thanjaiyali Nagar)

Three Alvars (Thirumangai Alvar, Bhoothathalvar and Nammalvar) are traditionally credited with mangalasasanam here, making Thiruthanjai Mamanikoil one of relatively few Divya Desams glorified by three different Alvars across three separate shrines within one complex. The town of Thanjavur itself is traditionally believed to take its name from this temple's founding legend, giving the Divya Desam an unusually direct link to the identity of the city that grew up around it.

Because the Alvars' verses address Thiruthanjai Mamanikoil, Manikundram and Thanjaiyali Nagar together whenever they mention "Thanjai," the three shrines have always been counted as a single Divya Desam rather than three separate entries among the 108, a distinction it shares with only a handful of other multi-shrine Divya Desams on this list.

Temple tradition holds that in the Treta Yuga, three demons (Tanchakan, Tantakan and Kacamukan) were blessed by Shiva and grew arrogant, troubling the sage Parashara as he performed penance nearby. Vishnu is said to have killed Tanchakan at this spot, and the town of Thanjavur is traditionally believed to take its name from him.

The temple is constructed in Dravidian style and is understood to date to the Chola period, consistent with its glorification in the Naalayira Divya Prabandham by Alvars active in the 6th-9th centuries CE. The Manikundram and Thanjaiyali Nagar shrines sit nearby on the banks of the Vennaaru river; every pasuram by Nammalvar and Thirumangai Alvar that mentions "Thanjai" is traditionally understood to refer to this three-shrine complex as a whole.

Manikundram has a small east-facing shrine with the deity and consort sharing one sanctum, under the Ambujavalli association; Thanjaiyali Nagar similarly houses Veera Narasimha Perumal in a small east-facing shrine under a tower called Vedasundara Vimanam, by its own Surya Pushkarani tank. Each of the three shrines therefore has its own distinct vimanam and theertham, even though all three are venerated together as one Divya Desam.

A multi-day Brahmotsavam, typically observed in the Tamil month of Panguni (March–April), is understood to be the principal annual festival across the complex, alongside the wider Vaikunta Ekadashi observance in Margazhi (December–January) common to Chola Nadu Vaishnava temples. Exact festival dates and scale can vary year to year. Check locally for the current calendar.

Daily worship follows the customary schedule of Chola Nadu Divya Desams across all three shrines.