Kumbh Mela festival
The subject of a Beatles song is among the many foreign pilgrims visiting India's Kumbh Mela festival.
Prudence Farrow, about whom John Lennon wrote the song Dear Prudence, is also sister of Hollywood actor Mia Farrow.
The Kumbh Mela, which is held every 12 years, is billed as the world's biggest gathering of humanity.
Millions of Hindu ascetics and pilgrims take a dip at Sangam, the confluence of the Ganges and Yamuna rivers in Allahabad city.
Ms Farrow says she waited for four decades to come to the Kumbh Mela.
She had first visited India in 1968 as a student of meditation and met the Beatles at Indian guru Maharishi Mahesh Yogi's retreat in Rishikesh.
"I wanted to come to the Kumbh with the Maharishi, but that never happened," she told the BBC. Her guru died in 2008.
This year Ms Farrow finally made it to the Kumbh Mela with her husband Albert Bruns.
"India has changed so much since I first came here," says Ms Farrow, 65, sitting in the brightly-painted porch of her rented flat in Allahabad.
"Back then it was exotic. We were staying in the forest outside Rishikesh. Life was quite agricultural even in the cities.
"There were animals on the road, there were very few telephones and there was hardly any electricity where we were staying."
Ms Farrow says she was in for a shock when she first arrived at the festival ground last month.
At first, she insisted on staying in one of the tens of thousands of tents that have been put up on the banks of the river.
Ms Farrow, who has a doctoral degree in South Asian studies and runs foundations to promote meditation, says she was in search of "an inner silence".
But, ironically, the blare of three loudspeakers every morning at the festival grounds shattered her peace and she shifted into the city.
This was, she says, in sharp contrast to the peaceful times she spent with her sister Mia at her guru's retreat in Rishikesh in 1968.
At the retreat, the Farrow sisters met the Beatles.
"Because of Mia there were too many people coming in and out of our block," says Ms Farrow.
"And then in the evenings George Harrison would jam with John Lennon and others would join in. I wasn't getting the silence.
"People said: 'You are being too fanatical, you should come out.' Yes, I was extreme because I thought it was a privileged time. I still think it was the most important time in my life."
So while the rest of the students partied, Ms Farrow says she locked herself up in her room and practised meditation.
That is when, she says, Lennon, wrote the song Dear Prudence, which appears on the band's White Album.
The song's hand-written lyrics, lined with doodles, sold at a Sotheby's auction in 1987 for $19,500 (£12,800).
"The reason he wrote I was beautiful - and there were much more beautiful people around - was because I was so much like George," says Ms Farrow.
"George and I were there for very much the same reasons - we were both very spiritual and we wanted to find a solution for ourselves and the world. George would say that through his music he wanted to help people become more settled, more quiet and more sensitive."
Ms Farrow says she did not want to meet the Beatles as "great people never lived up to their image".
Did they disappoint her?
"What didn't disappoint me was that they were still real people. They weren't more important than anybody else," says Ms Farrow.
"Fame has that quality - it corrupts you. You begin to feel that you're separate from other people, you're more powerful. But they didn't have that.
"They were going through the same things as we were. That's why they were the voice of the times."