"Kumbh Mela or Kumbha Mela is a mass Hindu pilgrimage of faith in which Hindus gather to bathe in a sacred river.
Traditionally, four fairs are widely recognized as the Kumbh Melas:
the Haridwar Kumbh Mela, the Allahabad Kumbh Mela,
the Nashik-Trimbakeshwar Simhastha and the Ujjain Simhastha,
These four fairs are held periodically at one of the following places by rotation: Haridwar, Allahabad, Nashik and Ujjain.
The main festival site is located on the banks of a river the Ganges
(Ganga) at Haridwar, the confluence of the Ganges and the Yamuna and the mythical Sarasvati at Allahabad, the Godavari at Nashik and the Shipra at Ujjain.
Bathing in these rivers is thought to cleanse a person of all sins.
At any given place, the Kumbh Mela is held once in 12 years. "