It’s late evening in the city of Prayagraj and the roadside vendors selling snacks are packing up their wares to shut for the night.

A little farther, Nagavalli Gupta reads a prayer book while her husband sits cross-legged wearing a woolen cap, wrapped in a blanket. They are from Bengaluru in the southern state of Karnataka and have been on a pilgrimage for the past two months.

India's Maha Kumbh Mela, or Great Pitcher Festival, is set to be the world's largest gathering of humanity, with 400 million visitors expected at the six-week event that began this week in the northern city of Prayagraj.

Tens of thousands of naked Hindu ascetics and millions of pilgrims took dips in freezing water at the confluence of sacred rivers in northern India on Tuesday.

Tens of thousands of naked Hindu ascetics and millions of pilgrims took dips in freezing water at the confluence of sacred rivers in northern India on Tuesday, in the first of a series of major baths in the Maha Kumbh festival,

Over about the next six weeks, Hindu pilgrims will gather at the confluence of three sacred rivers where they will take part in elaborate rituals.

Hindu devotees from across India flocked to the northern city of Prayagraj yesterday as the world's largest religious festival began. Over the coming 45 days, an estimated 400 million Hindus are expected to come together for Maha Kumbh Mela.