Tents covered the vast site of the Maha Kumbh Melha (Great Kumbh Fair) near Allahabad town, as pilgrims jostled with the naked Hindu ascetics brandishing fearsome-looking tridents, multitudes of beggars and Indian commandos patrolling the area to ward off any terrorist attacks.
Thousands of small boats were ferrying the devout to a spot where the Ganges and Yamuna rivers converge to allow them to bathe there.
The banks of the rivers resembled a sea of heads, stretching down to the water, as the devotees lined up to wash away their sins.
The latest Kumbh Mela festival, held once every 12 years, has been marked by aggressive marketing by corporates promoting new products and Internet websites advising stay-at-home pilgrims on how to take ritual baths in the comfort of their homes.
Ash-smeared sadhus (wandering ascetics), sporting marigold garlands, were marking their territory in enclosed spaces called "akharas" as loudhailers issued instructions to the milling crowds to prevent the deadly stampedes that have occurred in the past.
Some of the sadhus could be seen still carrying out penances they took on at the 1989 Kumbh Mela, standing on one leg, or keeping one arm continually raised in the air.
The Kumbh Mela festival has been overshadowed this year by the plans of hardline Hindu groups to unveil a model of a temple to the god Rama which they intend to construct over the ruins of a mosque razed by Hindu zealots in the northern town of Ayodhya in 1992.
The Vishwa Hindu Parishad (VHP, World Hindu Forum), which has close links to Prime Minister Atal Behari Vajpayee's party, also plans to announce the dates for the temple's construction, despite appeals by the government to avoid inflaming communal tensions.
Dharas Ramji, 65, from the northern Muslim-majority state of Kashmir, said he had come to Allahabad for both the pilgrimage and to support the temple campaign.
"I am here to see the Rama temple gets built and straight from here I will go to Ayodhya," said Ramji, who has the name of Rama tattooed on his face 100 times and sports on his arm a tattoo depicting the Hindu monkey god Hanuman.
"I've been a Ram devotee ever since my childhood. I would give my life for the Ram temple," he said
Large extended families, numbering 30 members or more, set up mini communities inside the tent city erected for the pilgrims, with makeshift communal kitchens and enough supplies for a month.
Ross Anthony, a 29-year-old British engineer who has visited India a dozen times, confessed to being dumbstruck.
"It's the sheer scale of the whole thing that is so mind-boggling. It's extraordinary to witness this sort of mass spritual communion between so many people and the river," Anthony said.
Compatriot Danny Sims said: "To be honest, I'm surprised at how clean everything is. You would get 10 times the amount of rubbish at a single music festival in Britain."
A German pilgrim, who identified himself by his Hindu name Datta Bharati, said he had cycled to Allahabad from his home in the Black Forest region.
"I started my journey on June 26, 2000 to reach the Kumbh Mela," he told the Press Trust of India.
"I sat on the cycle and chant 'Om Nama Shivaya' (Hail Lord Shiva) and all along I faced only friendly people."
Up to 70 million sadhus and pilgrims are expected to pass through the 42-day Kumbh Mela, which formally began on Tuesday.