Tens of thousands of Hindus seeking absolution of their sins immersed themselves on Monday in freezing waters at the confluence of sacred rivers, as India began a six-week festival expected to draw the world's largest gathering of humanity.

Held every 12 years, 2025's Maha Kumbh mela has seen the construction of 400km of temporary roads, a 10,000-acre pop-up tent city, 150,000 toilets, three hospitals and more.

The Maha Kumbh Mela has commenced in Uttar Pradesh’s Prayagraj on. The 45-day religious gathering is significant for Hindu pilgrims and devotees as the event marks the completion of 12 Kumbh Mela cycles,

The Maha Kumbh Mela, or the Great Pitcher Festival, will bring more than 400 million people to Prayagraj city in northern India over a period of six weeks starting Monday, making it the largest gathering of humanity in the world.

While the Kumbh Mela festival is ordinarly held every three years, rotating between several holy cities on the banks of these rivers, the Maha Kumbh Mela occurs only once every 12 years. Maha means “great”, and the event attracts the most devotees because it is considered the most auspicious and holy in the cycle.

The 45-day mega festival, from January 13 to February 26, is expected to draw a large number of tourists and cultural aficionados aiming to explore what is billed as one of the largest religious gatherings on earth.

Authorities in India are racing against time to get the city of Prayagraj ready to host the Hindu festival Kumbh Mela, described as humanity's biggest gathering. About 400 million pilgrims are expected to attend the 45-day spectacle, which is so large it can be seen from space.

India set for Hindu festival Maha Kumbh Mela | REUTERS WARNING: May contain nudity The Maha Kumbh Mela, the world’s largest gathering of humanity, begins in the northern Indian city of Prayagraj, with millions of devout Hindus arriving to take a dip in the holy river Ganga.