The Kumbh Mela festival, the largest religious gathering in the world, has begun in the northern Indian city of Prayagraj.

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.

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.