festival of Mahamaham Kumbakonam is called as " Temple City " because of the large number of temples within the town and the nearby areas. It is a very peaceful city and the festival of Mahamaham is celebrated every 12 years at the Mahamaham tank in Kumbakonam. http://www.onyxon.net/Saba/History.htm The festival takes place at a particular time as determined by astrological position: during the full moon of the Tamil month of Maasi (February-March) when the conjunction of the moon with the lunar asterism (Magha Nakshatra) and when Jupiter is in the constellation of Leo.This Festival occurs when the sun is in the Zodiacal sign of Aquarius(Khumbha), Jupiter transists Leo(Simha) and the Moon is in conjunction with the constellation Maham. Generally all the these astronomical combination take place on a full moon day of the Tamil Month of Masi(Solar Kumbha Month) i.e. either in the latter half of February or in the first of March. http://en.wikipedia.org/wiki/Mahamaham