The Maha Kumbh starts from Monday (January 14) and will last for over 55 days (ends on March 10).
It is regarded as a unique spectacle of colour, noise and Hindu devotion.
Worshippers believe a dip in the holy waters will cleanse them of their sins, and they have already begun arriving in the host town of Allahabad.
Millions more are on their way, heading for makeshift accommodation and campsites.
The Maha Kumbh organisers are preparing to receive at least 110 million people from all walks of life, with an average influx of around two million a day.
A total of 12,000 police officers have been deployed. The organisers have set up 35,000 toilets, 14 medical centres, 22,000 street lights, 150 kilometres of temporary roads, 18 bridges, and new sewage facilities.
Close Circuit Television Cameras have also been set up at strategic locations.
Nearly 7,000 buses and 750 trains are expected to ferry people to and from the main bathing area, where three giant "ghats" have been built enabling visitors to walk down steps into the sacred but heavily polluted water.
Many drink it, while others bottle it and take it home as a memento or a gift for relatives.
The biggest bathing days in 2013 will be January 14, January 27, February 10, February 25 and March 10.
The biggest day of all, when 20 million people are anticipated, will be "Basant Panchami" on February 15.
The bearded, naked and dreadlocked sadhus, running en masse into the water, brandishing tridents, swords and sticks at auspicious times on the important bathing days, will be one of the highlights of the festival.
Plastic bags and use of soaps has been banned. Pilgrims have also been instructed not to throw garlands and incense sticks into the water.
The Kumbh Mela has its origins in Hindu mythology, which tells how a few drops from a pitcher containing the nectar of immortality, are said to have fallen during a fight between gods and demons on the four locations across India which host the festival -- Allahabad, Nasik, Ujjain and Haridwar.
Allahabad: At least 100 million devotees, ranging from naked Nagas and their leaders to common Hindu worshippers, will stream into the city of Allahabad in Uttar Pradesh to take a dip at the confluence of the Rivers Ganges, Yamuna and the mythical Saraswati next week during the Maha Kumbh Mela or Festival, an event that takes place every 12 years.
First Published: Saturday, January 12, 2013, 12:05