A few minutes before midnight on Friday, June 15th, Elevationair, U2's US tour jet, prepares to make its last flight. If, as Bono sings on Kite, hip hop drives the big cars, then let it be known that U2 still fly the bloody big plane. The jet idling on the tarmac of Washington Dulles airport has been artfully decorated with the tour's heart-in-a-suitcase logo, right down to the custom-made head-rest covers. It looks like it might belong to an airline run by an eccentric, jolly billionaire.

Inside the plane, the cogs of the U2 machine are spinning busily. Manager Paul McGuinness, who will turn 50 in a few minutes, marches up and down, bristling with paperwork and purpose. Bobby Shriver, nephew of John F. Kennedy, brother-in-law of Arnold Schwarzenegger and Bono's ally in Washington, exudes bonhomie and flashes his Kennedy smile.

Among the Washington movers and shakers at tonight's show was Tipper Gore, wife of Al. Jesse Helms came the night before, although Edge notes that "I don't think he stayed till the end". But that was Washington and within an hour we will be in New York, a brief hop down the East Coast in this jet neatly illustrating the dichotomy between Statesman Bono and Rock Star Bono.

"My children will tell me to turn down my Bono-ness occasionally," he hoots. "I think it's something to do with going into one. You forget your circumstances, the laws of gravity, everything. I'm not sure [thoughtful and extremely long pause] what the thrill is of watching Bono. I think it must be something along the lines of the way you might watch one of those guys who jumps off tall buildings in New York with a few plastic bags as parachutes. It's a slightly will-he-or-won't-he thrill."

New York has long been U2's spiritual second home, celebrated as the ultimate getaway in the eponymous song on their career-reviving 10th album, All That You Can't Leave Behind. Like the subject of the song ("so not autobiographical," he insists), Bono has bought a place on the Upper West Side. Mullen and Clayton have bases here too, although their home is still Dublin. Only Edge has so far resisted the lure.

"You've got to spend enough time in a place to make it worthwhile," he reasons. "Otherwise it's just turning money into problems. That's Brian Eno's attitude to all possessions."

Upon touching down at JFK airport (or as Bobby Shriver might have it, Uncle Jack's), three-quarters of U2 scatter to their respective apartments, leaving Edge to savour the delights of Manhattan nightlife single-handedly. The following morning, Bono tells me something that would have come in handy a few hours earlier: "Edge only wakes up after midnight. He's an owl." True to form, Edge's promise of "just the one" turns out to mean just the one bottle of vodka. Tonight's club is Centro-Fly, home to a peroxide blonde DJ who takes the opportunity between mixes to slip the top of her dress down and dance topless on a podium. Shortly before 4.30 a.m., at which point our energy runs out before the vodka does, a girl walks up to Edge with a purposeful look in her eye.

"Are you a DJ?" she enquires.

"No," Edge politely replies. "I'm in U2."

"Oh," she says, unimpressed. "I thought I recognised you from somewhere."

Fortunately, such confusion isn't par for the course. It does, however, offer a glimpse of what might have been if U2 hadn't wrenched back their crown so successfully. Back in January, at their London Astoria show, Bono announced that they were re-applying for the post of Best Band In The World. If "best" is a matter of taste, then they have certainly regained enough commercial clout and cultural impact to stake a decent claim to the title. "A lot of that was bravado," Edge concedes. "I suppose the big issue for us was not so much, "Are we going to sell copies of this record?' It was more "Is U2 still relevant? Is rock 'n' roll still relevant? Or is this band and this form in a downward spiral?' And, to be honest, we didn't know." We are sitting in the dimly lit, self-consciously hip bar of the Time hotel the following evening. Edge has been drinking wine all afternoon at Paul McGuinness's birthday, which means that he's uncommonly talkative and prone to pinching cigarettes, but otherwise as calm and unruffled as ever. With his gentle manner and reassuring, avuncular smile, he is extraordinarily mellow company.

"Having deconstructed the band so ruthlessly over the previous couple of records," he says, "to bring it all back together again to celebrate the limitations of what a rock 'n' roll band, and this rock 'n' roll band, is about has given us a jolt of encouragement." Just as Rattle And Hum took U2's earnest, rootsy 1980s incarnation as far as it could go, the PopMart tour marked the outer limits of their futurist, irony-loving, lemon-toting phase. They wanted to redefine the possibilities of stadium rock, and they did that, but only by spending $250,000 a day and putting themselves through the physical and psychological wringer.

With Pop stiffing in America, and the press revelling in schadenfreude at every unfilled stadium seat, U2 had become, in Bono's words, "as cold as porridge. Eventually people get the message that you're not that interested in pop music and they leave you be."

When The Best Of 1980-1990, came out the following year, Edge had to force a reluctant Bono to sit down and listen to it. After running away from their past for most of the 1990s, U2 realised it was time to appreciate it again, in small doses at least.

The key moment came when Edge hit upon Beautiful Day's widescreen guitar chords and, after some initial cold feet, the group agreed that such a classic U2-ism was nothing to be ashamed of. "It was saying, fuck it, we are U2 and this is one of the things that we're known for doing well," asserts Edge. "It was kind of a nice feeling to reclaim the past."

In many ways, the world was ready for them to do just that. If their unlikely spell as underdogs after Pop made them more sympathetic to their critics, so did a star-free musical climate typified by Travis and Radiohead. In that context, All That You Can't Leave Behind's combination of vaulting ambition and anthemic, rock 'n' roll swagger has proved just the ticket.

"I think it probably took the acceptance of hip-hop culture and Oasis for critics to finally acknowledge that ambition isn't necessarily an indication of a lack of creative credibility," Edge muses.

"When we first came out we didn't share the ghetto mentality of a lot of UK bands. That was the cardinal sin."

He does not consider his lifestyle in any way extravagant, just as he has no sleepless nights over any of the trappings of success. His top tip for anxious rock stars is to relax and not take any of it too seriously. And find a good
frontman to hide behind.

"I think that's why in some ways the band works," he says cheerily. "Bono loves nothing better than being in the spotlight and I don't think anyone else is that interested in it. I'm the perfect sideman."

Who doesn't call you Edge? "Immigration officials. That's about it these days. I don't like people calling me by my birth name. It seems like an attempt at familiarity which doesn't work."

A lot of this album is about coming to terms with age and responsibility. When did you feel that you'd grown up?

"I'm not sure if I know what it means. When you're a kid you're aware of the icons of manhood, like James Bond or whatever, but it's quite startling to realise that William Hague is younger than you. I think rock 'n' roll is a naive
form, it defies analysis. If you ever really become grown up I don't think you can possibly do it, so I suppose I never really want to grow up."

Madison Square Garden, Sunday night. The "woo-hoo"s of Elevation strike up and the new U2 live experience prepares to take Manhattan. After the media-literate, hi-tech hi-jinx of the past 10 years it is strikingly sparse: a blast of acid flashback rave visuals during The Fly, mocking footage of NRA cheerleader Charlton Heston before Bullet The Blue Sky, but no giant elevators or kite-shaped walls of TV screens.

But it is the first time that different chapters in U2 history have been so deftly reconciled: they move from a delicate, acoustic Stay ("We recorded this in Berlin at the start of the 1990s, when you Americans thought we'd gone all arty") to a hysteria-inducing Where The Streets Have No Name, without missing a beat.

Bono describes it as "a love fest". The stage has been constructed in the shape of a heart, with a small enclosure for early-bird ticket-holders circumscribed by platforms that extend halfway into the arena. During Until The End Of The World Bono crouches down so close that hyperventilating crowd members can tug at the sleeves of his leather jacket. You half expect the lame to throw their crutches in the air and lepers to jig about shouting, "Hallelujah!"

"Yeah, it's the gospel tent," agrees Bono afterwards, adopting the tones of a Deep South minister. "A revival happening!" Tonight's hot-ticket status is confirmed by the crowd in the raised VIP enclosure: Winona Ryder, Christy Turlington, Ronan Keating, Beastie Boy Adam Horowitz and designer Bruce Weber, with Courtney Love, Moby and Tiger Woods down for the following night. There is also a distinguished-looking couple who, it transpires, are Adam Clayton's parents. With maternal pride, Mrs Clayton gives her son a wave.

Afterwards the Fun Lovin' Criminals, who supported U2 on PopMart, throw a party at the club Shine. One member of U2, however, goes for "half a drink" and then beats a hasty retreat ... "Sometimes you can tolerate stuff like that, other times you can't," frowns Larry Mullen Jr, perched on a sofa in the Time bar the following lunchtime. "I'm not built for the schmooze. I'm not good at small talk. I've got about one hand of friends [holding up five fingers] and a few acquaintances. I'm cautious by nature and I don't like bullshit, so that doesn't bode well for being in a band."

Are you immune to all the dazzle? "Immune is not the word I would use. Immune conjures up an image of somebody who is above it. I think I'm below it." Bono once quipped that Mullen was Dorian Gray and he was the decaying picture in the drummer's attic. The perpetually handsome Mullen appears to have stopped ageing around the time of The Joshua Tree.

"Some people would say I'm lucky," he smiles. "I'd say ... [pondering, then brightening] I'm lucky!" He also retains a youthful purity of purpose and disdain for anything not directly related to either his family, U2 or drumming. Even the few seconds between songs are hard going, especially returning to an intimate stage set-up after years of stadiums.

"It's an odd sensation when you have people in the front who can actually see you smiling or see you grimacing," says Mullen, grimacing. "Between songs people look at you, so I'm thinking when I'm holding the sticks, 'Do I look bored? What sort of expression should I have on my face? Should I have an expression on my face?' I find myself cringing sometimes." And he cringes on cue.

When Bono introduces the band on-stage, a habit he's only developed on this tour, he gestures to the drummer saying, "For a whole lunch break we were called the Larry Mullen Band." Mullen denies that this historical quirk has anything to do with his proprietorial attitude to U2, but is well aware that outsiders see him as the resident spoilsport, tutting disapprovingly at any departure from old-fashioned rock 'n' roll values. This is, after all, the man who called his son Elvis and, with his crewcut and bowling shirt, looks like he would be most at home propping up the jukebox in a 1950s diner. He begs to differ.

"The perception is that if you say 'hold on a minute', it means no," he protests. "It's not about that. I suppose I think differently from the other three guys in the band. I don't like to make decisions quickly. In the excitement of a moment people agree to do things that are not good for the band and not good for them and I try to protect the band as much as I can." Is your own ego less important than the band, then? "No, it's a band ego," he says. [Grinning] "It's a bit like joining the priesthood or the Mob. The only way you get out is when you die or when somebody whacks you. And there's a selfish side to it. This has been my life since I was a kid. I don't want it to go pear-shaped."

During the making of the album, were you concerned that Bono's political activities were getting in the way? "I think it's still an issue," he says firmly. "I admire him for doing it, but it creates serious, serious difficulties. He's running around trying to do everything and keep everybody happy. The reality is it's probably the most important thing he's going to do in his life, so my attitude would be, take a year out and do it properly." Mullen doesn't have much time for extra-curricular activities ("We could be into fish farming but, y'know, there'll be time for that"), but he likes to read. He has a friend in New York who mails him books he might like, and they help him keep his head together while he's on tour.

"It's a world within a world and when you stop and try to get off it's weird," he says, screwing up his face. "Sometimes I find myself at home and someone says, 'Would you mind moving that?' and I say, 'Surely somebody else should be doing this?' 'No, it's your house.' It's a mad thing we do. There's nothing natural about it. I mean, I hit things for a living. I hit things and people clap!"

And it doesn't get less weird as the years go by? "No, it gets more weird. You have to work harder because the goalposts have changed. It's about your integrity, you want your family to be proud of you. I have nightmares of my kids saying, 'Did you really look like that? Did you really make that shit?' I want to make good enough records for them to be able to say I'm OK."

Adam Clayton first came to live in New York in the aftermath of the Zoo TV tour, and spent six months "decompressing". He is, therefore, no stranger to the white heat of a Manhattan summer and bustles down the scorching uptown sidewalks in full Englishman-abroad, hot-weather attire: sandals, shorts, T-shirt and sun hat.

In one hand he precariously balances two varieties of Starbucks coffee. In the other he clutches a mobile phone and on his back he wears a natty deckchair-cum-rucksack with which he is extremely chuffed. As Larry Mullen Jr notes, "It's the little things that get you through when you're on tour." We stroll into Central Park, sidestepping the joggers, rollerbladers and cyclists, until Clayton decides we've found the perfect spot. "Today we're going to do something healthy," he announces in his curiously posh drawl, unfolding his deckchair and removing his T-shirt. "We're going to watch other people exercise."

Clayton has the languor and bone-dry humour of a disgraced aristocrat exiled to the colonies for some colourful indiscretion. Bono has taken to teasingly introducing him on-stage as "the poshest member of U2", but the Oxfordshire-born bassist isn't convinced his non-working-class, non-Irish status is particularly significant.

"You know, if you're just another arsehole from the suburbs, I think it's pretty understandable if one was offered a chance to take on the world and win, you'd go for it," he contends. "I wasn't destined for greatness in any other area. I'd have ended up being some kind of bad landscape gardener or something. So I much prefer this."

It was Clayton, of course, who flew the flag highest for rock 'n' roll antics during the Zoo TV tour: getting engaged to Naomi Campbell, displaying his penis on the sleeve of Achtung Baby and turning partying into a full-time occupation. Even during the 1980s, when stony faces peered out from beneath wide-brimmed hats, he was the only member with neither a long-term relationship nor strong religious beliefs: "I did have a lot of energy for hanging with people, checking things out, just absorbing."

For his birthday one year, the rest of the band bought him a travelling cocktail cabinet. Bono reveals that "we lived through him vicariously for a few years. I was hoping that he'd do something like buy a yacht and we could all hang out on it. Because all of us were too embarrassed."

Bono describes Clayton now as "a Buddha". Apart from cigarettes, which he chain smokes with heroic stamina, the bassist abandoned all his vices when he gave up drinking in 1996. He also got rid of many of his possessions, including the cars
and his extravagant wine cellar. "I think one of the great things about bands is that they allow you to be irresponsible for longer. Whether or not in the end that's a really healthy position to take ... I guess I've been lucky in that I fucked about until my mid-thirties and now I can have more of a balanced outlook. I think not having a family and kids, I know what I need. It's not very much actually, which is a nice place to be. Part of it's just opening your eyes and realising that there are practical ways that people live and that's OK. There's nothing wrong with catching the subway in New York - you don't have to get a stretch limo."

Clayton could hold seminars in How To Be In An Enormously Successful Rock Group And Not Go Mad. He appears to be perfectly content with his place in the scheme of things. On the subject of fame he chortles, "I'm famous 'cos I know Bono. That's pretty much it."

So do you ever visualise what life beyond U2 might be like? "Not so much now. Occasionally I have fantasised about it, but it's kind of pointless to think a life beyond U2 could in any way measure up to a life with U2. You can't get out
of this club. It's like the guys in The Beatles. They're still in The Beatles." Spending a few days around U2 confirms that punctuality is not one of Bono's strong points. It's as if in order to pack so much into his life he has to
believe that time is elastic and it's the job of everybody around him to remind
him that it's not.

An hour later than scheduled, he is all charm and apologies as he sweeps into Pastis, a vogueish Greenwich Village bistro where the brunching hipsters are too cool to ask for an autograph, but not too cool to stare. He cuts an impressive
dash in a playboyish cream suit and a black shirt, unbuttoned almost to the navel to reveal a rosary nestling in a healthy chest rug.

"Wine bar chic," he winks. "It's coming back."

Bono's hair is jet black but the bristles on his chin are flecked silver and there are deep lines under his eyes. It's a face that looks lived-in, and lived in well. Apart from his compact height (five feet six inches) he radiates largeness. He punctuates his speech with acrobatic hand gestures and a generous laugh, marking revelations or particularly quotable aphorisms with a conspiratorial glance. His charm is nuclear.

What's the hardest part of U2's past to come to terms with? "There were a lot of unfinished lyrics that were written in five minutes instead of five hours. I remember the 1980s for that. The first two lines of Where The Streets Have No Name were just written on the mic - [dismissively] I want to run, I want to hide, I want to tear down the walls that hold me inside. It's like teenage poetry! The idea behind the song, the idea that you can transcend where you are, the idea of music as a sacrament, is so powerful, but it's this inane couplet. [Chuckles] Those sort of things."

Has that line about "mid-life crisis" in the song New York dogged you? "It followed me around, but everyone who knows me knows that I had a mid-life crisis when I was about 27. And at the moment I'm on retreat, I mean in the meditative sense rather than surrender. I'm in a very blissed-out state. I'm really excited about getting older because all my heroes are in their fifties and sixties. I do think that when I'm 60 I will finally be cool. Not that that is high up on my list, but I will be and so will a lot of my mates. We're going to be badass." Fame, Bono contends, is "obscene". His advice to anyone dealing with it is to surround yourself with the right people. He has many friends, some famous (the rest of U2, Wim Wenders), most of them not, and describes himself as "a very loyal, if unreliable, friend".

"In that sense, I'm quite Italian. They're family. If you're smart you create a world where you shrink in size and then you find oxygen and room to maneuvre. If you're not, then you shrink your world and tower above it, which is my experience of a lot of folk."

He laughs self-consciously. "I think I just said I was smart there. I'm sorry about that."

Who intimidates you? "When I meet my maker. The rest are easy."

Bono has had good reason to ponder his maker of late. There's death lurking in the corners of All That You Can't Leave Behind, and the more you discover about these songs, the further out of the shadows it creeps. First came the revelation
that Stuck In A Moment You Can't Get Out Of was inspired by the death of Bono and Edge's friend, Michael Hutchence. Then in April, Joey Ramone, an early influence on U2, died of cancer while listening to In A Little While, turning a song written about a hangover into a lullaby for a man's last night on Earth. It's a dark record, isn't it?

"Yeah, there was some dark stuff going around. I'd be lying to you if I said that there was no appeal to me in the, y'know, the abyss. Everyone wants to slip out of daylight and into the shadows. It's a more comfortable place to be
sometimes."

What's the most important belief you've left behind over the years? "That innocence is more powerful than experience. Anton Corbijn did a museum retrospective in Holland, with a room full of Bonos, which was a little disturbing. There was one photo where I saw a face that I don't see any more when I look in the mirror. It's nothing to do with youth - it was a look in the eye and I think it probably got beaten out of me by the journey. It's the power of innocence."

Back at Madison Square Garden, there are ghosts circling the arena. Bono precedes Stuck In A Moment You Can't Get Out Of with an a cappella version of the Beatles' In My Life: "Lovers and friends I still can recall, some are dead and some are living."

Before In A Little While he says, "This is a good song but Joey Ramone made it a great one. He's changed it for me forever. I want to say to New York City that The Ramones were ground zero for us. It's where we started." That was almost 25 years ago. Since then?

Punk rock; bad hair; Live Aid; stadium rock; winning America; going too far; buying boy toys; going arty; losing America; playing Sarajevo; riding the lemon; meeting the Pope. And now? Maybe being the biggest band in the world again, if
they fancy it.

"Ah, forget the biggest," scoffs Bono. "Disneyland is big. On one level I feel that if you're shy and want to make private work for your friends, be a potter! But what I mean by the band is The One. It's something to do with the moment that music breaks out of its box and suddenly is relevant to a wider world." His hands soar and sweep. "It's the embrace of it. That's what turns us on."