The Mahamaham tank is the spiritual centre of Kumbakonam — a large, roughly square stone-stepped reservoir said to be filled by the nine sacred rivers of India once every twelve years, when Jupiter enters the constellation of Leo. The accompanying Mahamaham festival is one of the largest religious gatherings in South India; the 2016 festival drew over three million pilgrims to a town of fewer than 150,000 residents.
Even outside festival years the tank is the busiest spot in town. Sixteen small mandapams (pillared pavilions), each dedicated to a different deity, ring the water; pilgrims bathe in the early morning, and worshippers move from temple to temple around its banks throughout the day. Walk a slow circuit at sunset — the light on the water and the surrounding gopurams is unforgettable.