What is the Kumbh Mela, and why is it held in four cities periodically? What is Ardh Kumbh and Maha Kumbh? What is the origin of this pilgrimage festival?

Millions of Hindu pilgrims gathered on Tuesday at the confluence of the Ganges, Yamuna and Sarasvati rivers to take part in the first holy bath of the Kumbh Mela, the world's largest religious gathering.

Hindu devotees from across India flocked to the northern city of Prayagraj yesterday as the world's largest religious festival began. Over the coming 45 days, an estimated 400 million Hindus are expected to come together for Maha Kumbh Mela.

The Hindu festival of Kumbh Mela, associated with ancient traditions, has taken a step towards digitalization this year with the use of immersive technology or drone shows that tell the main legends of Hinduism,