The largest gathering of humanity on the planet began on Tuesday, with tens of millions showered in rose petals and holy ash at a spectacular Hindu festival on India's sacred riverbanks.

The Kumbh Mela is expected to attract more than 100 million pilgrims to Allahabad – recently renamed Prayagraj –over the next seven weeks to bathe in waters considered among the holiest in Hinduism.

Allahabad rises alongside the Ganges, Yamuna and mythical Saraswati, and the banks of these hallowed rivers have transformed into a riot of colour for the centuries-old festival.

A gigantic tent city has emerged near the confluence of the rivers, where Hindus believe bathing during the Kumbh helps cleanse sins and brings salvation.