A famous Hindu temple of Lord Shiva in Tamil Nadu. A prominent Saivaite centre. It is closely associated with the Kumbamela rituals held once in 12 years at the Mahamaham tank, which is nearby.
Legend is that at the time of Pralaya (deluge by water) Lord Brahma kept the seed of creation by dipping it in Amrith (Nectar) in an earthly pot (Kumba). He kept the pot at the peak of Meru Parvat (Meru Mountain – the cosmic abode of Gods in Hinduism)
But, during the Pralay, this kumba (pot) was carried out by water currents. But, when it reached the Kumbakonam, it got stuck there.
After the Pralay is over, Lord Brahma requested Lord Shiva to retrieve the seed of creation so that he can recreate the universe out of that. Lord Shiva, in disguise as a Kiratha (hunter), reached Kumbakonam. He broke the Kumba (pot) by sending an arrow; retrieved the seed of creation and gave that back to Lord Brahma.
Meanwhile, when Shiva broke the Kumba, the Amrith (Nectar) inside it spread around; drops of it fell on many places around the land. These places later became divine centres of Lord Shiva worship. Few drops of the nectar fell at the Mahamaham tank at Kumbakonam, making it so sacred and a venue of the Kumbamela.
Kiratha used the mud of the broken kumba (pot) to make a Shiva Linga. He himself entered on that Linga making it immortal and so sacred. This is said to be the Linga that we saw at the Sanctum Sanctorum of this temple. The name Aadi Kumbeswarar means that one who entered the Kumba (Pot) long long ago.
Goddess Parvati at this temple is known as Mangalambigai.