India's Kumbh Mela festival is billed as the world's biggest gathering of people.
Between now and March organisers expect about 120 million pilgrims to bathe at the Sangam - the confluence of the Ganges, the Yamuna and the mythical Saraswati rivers.
Hindus believe that doing so will cleanse them of their sins and help them attain "moksha", setting them free from the cycle of birth and death.
So how does one prepare for a gathering of humanity so mammoth it can be seen from outer space?
The mela (Hindi for fair) is held in the northern city of Allahabad (recently renamed Prayagraj) every 12 years.