India began on Monday its Maha Kumbh Mela, or Great Pitcher Festival, which is expected to draw more than 400 million visitors to the northern city of Prayagraj over six weeks, making for the largest gathering of humanity in the world.

Millions of Hindu devotees, mystics and holy men and women from all across India flocked to the northern city of Prayagraj on Monday to kickstart what is being touted as the world’s largest religious gathering.

Held every 12 years, the Maha Kumbh Mela or Great Pitcher Festival, as the religious event in the city of Prayagraj in the northern state of Uttar Pradesh is called, attracts more than 400 million visitors, both Indians and tourists.