The Marriage Ceremonial fire still burns. The marriage is between Shiva and Parvati, the Homa kunda is for their marriage. Yet the Temple is dedicated to Lord Vishnu!
The marriage of Shiva and Parvathi coud have played out again towards the end of Dwapara Yuga as well around 5000 years ago! Now to the Mango Tree at Ekambareswarar temple being 3500 years may be validated by this calculation.