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.

Touted as an event for spiritual purificationin Hinduism, Kumbh Mela takes place approximately every 12 years at four locations -.Kumbh Mela, Maha Kumbh Mela, Prayagraj Kumbh Mela, Haridwar Kumbh Mela,

Millions of Hindu devotees and mystics have gathered in the northern Indian city of Prayagraj for the Maha Kumbh festival, which is the largest religious congregation on earth