Tune in to "The CBS Evening News" tonight and Monday to watch Holly Williams report from the largest religious festival in the world.
Nobody is quite sure about the origins of the Maha Kumbh Mela - the bathing ritual performed by millions of Hindus once every twelve years. Like so much else in India's ancient civilization, the Kumbh Mela's beginnings are obscured by the mists of time.
A Chinese monk - Xuanzang - witnessed the festival in the 7th Century, and was the first to give a written account.
In the 1890s, Mark Twain was probably the first American to see throngs of Indians immersing themselves in the waters at Prayag, on the banks of the Ganges - the mighty river that nurtured India's 5,000-year-old civilization.
Twain thought that it was "wonderful" that "multitudes upon multitudes" made the arduous pilgrimage to the Kumbh Mela "without hesitation or complaint."
Today, the most important festival on the Hindu calendar - which lasts for nearly two months - still has the power to draw believers, who number around 800 million worldwide.
This year, organizers are preparing for up to 40 million pilgrims on Sunday, considered by Hindus to be the most auspicious day for bathing. They'll be accommodated in a sprawling, pop-up city of tents, complete with its own mobile banks, police force and post office.
Extra trains and flights have been added to transport floods of the faithful, but many are making their journey by foot, carrying their possession on their heads.
One of them is Om Kumar, a wheat farmer from Bihar in central India, who walked 300 miles to take a dip.
"I came for the water," he told CBS News. "It has special powers."
"This is part of our culture," said Himani Naggi, a postgraduate math student from Kashmir in India's far north, who travelled with her parents on a 1,000-mile train journey to Prayag. "This is how we get to heaven."
According to Hindu belief, bathing during the Maha Kumbh Mela can wash away ones sins, freeing the soul to escape the cycle of reincarnation. Early each morning pilgrims can be seen offering prayers to Lord Surya - the sun god - as they set Chrysanthemums and votive candles afloat on the water.
In a country where traditional farming villages co-exist with high-tech hubs, the Kumbh Mela also offers a fascinating cross section of modern India.
While most pilgrims endure basic accommodation under canvas, a wealthy few are pampered in luxury tented camps with en suite bathrooms and uniformed staff.
One of them is the Maharani Radika Raje Gaekwad - an Indian princess who normally lives in a palace in the state of Gujarat, and who describes the Kumbh Mela as "humbling."
"There's something that binds you all together - that faith in the Ganges, in the Kumbh, in your gods," she told CBS News. "We are one."