The Maha Kumbh Mela, or Hindu pitcher festival, begins Monday in the northern Indian city of Prayagraj. Officials expect at least 400 million attendees over the next 45 days.

Over the coming 45 days, an estimated 400 million Hindus are expected to come together for Maha Kumbh Mela. The festival is held every 12 years but the "Maha" or grand Kumbh Mela takes place only every 144 years, "marking the 12th Kumbh Mela and a special celestial alignment of the sun, moon and Jupiter", said The Guardian.

Millions of people are gathering in the northern Indian city of Prayagraj in Uttar Pradesh state to participate in the Mahakumbh Mela, the world's largest gathering of humanity.