Kumbha (Kumbha means pot) Mela is a sacred Hindu pilgrimage that takes place at the following four locations of India 
Prayag (near the city of Allahabad, in the state of Uttar Pradesh) at the confluence of three rivers Ganga (Ganges), Yamuna and Saraswati 
Haridwar (in the state of Uttarakhand) where the river Ganga enters the plains from Himalayas 
Ujjain (in Madhya Pradesh), on the banks of Ksipra river, and 
Nasik (in Maharashtra) on the banks of Godavari river. 
The pilgrimage occurs four times every twelve years, once at each of the four locations. Each twelve-year cycle includes the Maha (great) Kumbha Mela at Prayag, attended by millions of people, making it the largest pilgrimage gathering around the world.