It is certainly the most famous zebra crossing in Britain; it is probably the most famous zebra crossing in the world. People have come to walk, dance or skate over it, some from thousands of miles away; they have kissed its stripes, stripped on it, sung songs to it and written on it. It is on the cover of the current Rough Guide to England, and the subject of countless pastiche student posters. It is, of course, in Abbey Road, London NW8, and was made immortal on 8 August 1969, when the Beatles walked across it for the cover shot of the last album they recorded, Abbey Road, made at EMI's studios at No 3.

Nearly 25 years later, the Abbey Road zebra crossing has attained a status somewhere between Big Ben and the shrine at Lourdes. Every day, groups of devotees come to stand beside its orange beacons, staring at the stripes as if some of the moptops' genius might still be contained there.

'I feel awestruck,' says Richard Hession, a 23-year-old from Bristol. He begins to walk slowly over the crossing. Cars and taxis wait patiently for him; they know what this is all about. 'To actually be in the same place,' says Richard. 'It makes you think, wow] They were here. It makes you think about the past. It makes you realise that no one else will ever be that great.'

Nominally, the crossing only serves two mansion blocks on either side of the road; in reality, it is continually tramped over by Beatles impersonators. 'They come along in the middle of the night,' says Sgt Peter McGoay from St John's Wood police station. 'Two o'clock in the morning, you're driving down Abbey Road and there's groups of them walking across. Mostly Japanese, I don't know why.'

'I think that's something to do with Yoko Ono,' says Les, the porter at Neville Court, the red-brick block visible on the right-hand side of the album cover. 'I was opening up once at five in the morning and someone was on the crossing with nothing on. I suppose they wanted to do it when there was no traffic.

'There have been some very near misses. People cross over and forget about the traffic; and foreigners look the wrong way.'

Richard Porter, 33, president of the London Beatles Fan Club, brings scores of devotees twice weekly to the crossing on his 'Beatles London' walks. A 'second-generation' fan, Mr Porter relates with uncontained joy the moment he saw and was acknowledged by Paul McCartney on the crossing. 'We had a tip-off he was going up to the studios. We all shouted over. He couldn't believe we were there]'

According to Mr Porter, the crossing is the reason most people go on his three-hour tour. 'I did a survey and 95 per cent said this was the thing they most wanted to see.'

Armed with a clipboard, portable cassette recorder and permanent grin, Mr Porter leads his group out of St John's Wood tube station and down to Abbey Road. As they near the crossing, the excitement is palpable; the 45-strong group know this is a seminal moment in the life of a proper Beatles fan.

They walk over the crossing respectfully and gather in a throng to hear the story of the album cover, which they all know backwards already. Over the road, a Japanese-speaking tour is going through precisely the same details.

'The 'Paul is dead' rumour,' grins Mr Porter. His charges smile respectfully.

For those who don't know the myth, the 'Paul is dead' rumour was hatched in 1969 by a DJ in Detroit, a month after the release of Abbey Road. The tale, which was circulated widely, is that Paul McCartney died in a car crash in 1966 and the clues are all on the album cover.

Paul is barefoot, to symbolise a corpse; George, behind him, in a denim shirt, is the gravedigger; Ringo, in black, is the undertaker; and John, who leads the parade over the crossing in a white suit, is obviously a priest.

Behind the Fab Four is a Volkswagen 'Beetle' car, whose number- plate, LMW 28IF, has been interpreted to read 'Linda McCartney: Widow', and Paul would have been 28 IF he had lived (wrong - he was 27 at the time of the photograph).

Paul is pictured as being out-of- step with the other three Beatles. Turn the album over, and the flickering shadow over the tiled Abbey Road sign is said to look like his skull. In addition, 'The Beatles', written on the back of the cover, is cracked through - a clear premonition of their future collapse.

Though the myth was widely debunked, true devotees never mind hearing it again. As Mr Porter listed the clues, they nod knowingly; the tape recorder blasts out 'Maxwell's Silver Hammer'.

Perhaps the crossing is important because it signifies the last album that the Beatles recorded, or perhaps because it is the only readily available site closely associated with them. Much of Sixties London and Liverpool has gone, yet Abbey Road has changed little.

'I feel like I've come to a shrine,' says Alison Wiley from New York.

'This means everything . . . everything,' says Steve Vaughan, from Massachusetts.

'Everything the Beatles ever did happened right here,' says his brother Alan, waving at the crossing. 'It's better than Graceland.'

Regardless of the freezing weather, Alan is taking his shoes and socks off. He grasps a cigarette in the correct hand and proceeds to organise a Beatles formation across the crossing. 'Right, you be John, you be Ringo and you can be George. I'm Paul,' he says, hopping up and down.

Then a Danish group arrives and spends the next 15 minutes crossing and re-crossing the road, much to the irritation of a Hoppa bus. In the meantime, a bunch of Japanese have appeared and are writing their names on the Belisha beacons. The walls surrounding the studios nearby are also covered with scrawled messages, although a man from EMI whitewashes them every three months.

Residents in this otherwise quiet, leafy street regard such behaviour with amused tolerance. The film columnist Peter Noble, an old friend of the Fab Four, whose home, number 46, is featured in a forthcoming guide to the Beatles' London, says: 'We used to have a Westminster Council Abbey Road sign up on our house; it was never there for more than a week. Japanese fans came along with screwdrivers in the middle of the night.'

'I quite enjoy it when they get the wrong crossing,' says Nick Kent, artistic director of north London's Tricycle Theatre and another local resident. 'The sad thing is that there are other zebra crossings on Abbey Road and you often see fans posing on the wrong one. Do I tell them their mistake? Of course not. It would spoil their pleasure.'

Beatles' London walks: Sundays, Tottenham Court Road station, 11am; Thursdays, Baker Street station, 11am. Japanese tours: Mondays, Wednesdays and Fridays, St John's Wood station, 2.30pm.

'Beatles London', by Piet Schreuders, Mark Lewisohn and Adam Smith, published by Hamlyn, 28 April, pounds 6.99.

(Photographs omitted)