Gallery: Kumbh Mela -- the world's biggest religious festival Over 55 days from January 13, an estimated 100 million Hindu devotees will make their way to the Kumbh Mela religious celebration in Allahabad in the north Indian state of Uttar Pradesh. Here, a sadhu -- or holy man -- walks on the vast grounds at the confluence of the rivers Yamuna and Ganges where the devotees will congregate.