Bean is also there in her pushchair, wrapped in a big white woolly jacket. She's with her 21-year-old nanny, Cali, who looks as though he should be in the band rather than looking after the baby. Kurt's been posing for various photographers all afternoon and the most animated he gets is when he stands on a piece of glass without his sneakers on.

Chris Novoselic comes up on to the roof with a freshly-made mixed fruit drink and sits down. He's taken off the bear suit, which made him look even more toweringly tall than usual and which made him so hot he spent much of the photo session lying horizontal in front of a fan. After some idle chat, he starts talking about the interview we'd done a few days earlier in the hotel conference room. Cobain might have angrily written in the sleeve notes of the "Incesticide" compilation: "If any of you in any way hate homosexuals, people of different colour, or women, please do this one favour for us - leave us the fuck alone! Don't come to any of our shows and don't buy our records." But Novoselic is the self-appointed politico of the band as much as he is an off-kilter wag. He'd tried to steer the conversation away from Croatia, where his parents were born and brought up before moving to California, or Clinton, who he still believes is the best of a bad bunch, but the topics came up time and again.

As we sit watching the sun set, he says he's worried he might come across as being "too heavy" in print. I remind him that as well as talking about his involvement in projects such as the Balkan Women's Aid Fund, he also described the early days of Nirvana, then called Skid Row and influenced by Black Sabbath and Black Flag. And how he and Kurt, who both grew up in Aberdeen, a redneck backwater near-ish Seattle, were always in different bands. "One of The Melvins [still one of Nirvana's favourite bands] would join for a while, but it was never serious. Finally, back in '87, Kurt and I got together and decided to start a real band. So we found this drummer, scrounged equipment and rehearsed constantly. I used to take things so seriously, I'd get all pissed off if we had a bad rehearsal: God, it's gotta be good, it's gotta be rock, it's gotta be fucking fun.

"And we were lucky 'cause we had a van - we were the only band signed to Sub Pop at that time with a van. It was even mentioned in our press release. There was always something around the corner, a show in Olympia, in Seattle, an opening for the Butthole Surfers or Soundgarden. I can remember Soundgarden signing to a major for something like $175,000 and I was incredulous. What were they going to do with it all?" With the money Chris later earned from being in Nirvana, he bought a "modest house" in Seattle and a run-down 40-acre farm, three hours' drive from the city. There are no phones out there and that's just how he wants it.

At around the same time money began coming in, Chris started to have recurring dreams about being naked in public. "I guess the transition thing happened so fast." Various interviews last year quoted him as saying he'd got into drink too heavily and had consequently given it up. "Not really, I've been pretty consistent with the drinking. I just made it through. I had to experience all kinds of feelings and stuff. Being famous, the band... but I came out of it a better person. Much stronger and more mature. I just worked things out, accepted things. I have a way of not dealing with things. I've got to work on that." His wife helped him out, "just by being there to turn to, to be on your side - you need someone to crawl to".

The only one crawling around on the studio roof is Frances Bean. Chris finishes his drink and, still concerned, asks once more: "If you're sure I'm not too much of a hippy dippy... "

NIRVANA ARRIVE ON STAGE. They open with "Serve The Servants", the first song on "In Utero". The opening words are very Kurt - "Teenage angst has paid off well/Now I'm bored and old". The crowd, which is very male, very macho, get straight into mosh mania. Kurt later expresses his disgust at the high "meathead" quota, saying it's not normally that gender imbalanced. The audience can't seem to get enough of the succession of new material which opens the first part of the show. Familiar songs - "Lithium", even "Teen Spirit", which the band keep promising themselves they'll never perform again - are greeted with increasing enthusiasm. At its best, this could be pure '77 punk revisited. Big John, Kurt's guitar roadie and former member of the fairly dismal British punk band the Exploited, joins in on guitar for a few numbers; this succeeds, but the cellist who comes on for the acoustic numbers at the end is lost somewhere in the system. The band, all seated, have been too ambitious with this idea; what could have been a curious side to Nirvana is too quiet to even hear.

After the gig, Kurt looks crap. His skin is blotchy and he looks as though all the energy's been sapped out of him. When asked if he's ready for the interview, he smiles weakly and says, "Yeah, sure."

"I'M STILL TOTALLY NARCISSISTIC, I still hate the majority of the world. But not with as much venom as I used to. To hate that much is a matter of being naive. Maybe that negativity has to do with not being in love or being lonely or not having a child." There's a glimmer of a smile here. "Certain things just force you into being more positive and I'm really grateful for them. I got sick of myself, I was sick of myself for so many years. I was a punk rocker hating everybody. Sometimes, looking back on it, I couldn't imagine what I was like to some people."

It's 1.30am. Kurt has had a shower and has come up to my hotel room, where MTV flickers silently in the corner. He lies on the bed, head propped up on two over-sized pillows. He seems in a mellow mood. In two hours he moves only to the visit the bathroom, to reach for another cigarette or to take a sip of Evian. He talks softly. He's not keen on the backdrop of New York - "I hate this fucking city" - but says this is the first time he has had any fun talking to journalists. "I really, really enjoy doing every interview for this album 'cause I've things to talk about. I want to defend myself. All this bullshit which has been printed about us is reason enough for dialogue. " He laughs and draws hard on his cigarette. "I also have something to say about our album other than: 'Er... most of my lyrics are poems, you know. "'

Everything in Kurt (and Courtney's) public and private life has been scrutinised under a magnifying glass. No escape. The heat of the spotlight may seem to have fucked Kurt up, but then he'll tell you he was fucked up anyway. "I had a shitty life till I was about 17. 1 sat in my room for 90 per cent of the time. I'd go home after school, play my guitar and listen to music. The States seemed so big to me that I thought I'd never leave the region. At a younger age, everything seemed so simple and easy, I thought I could be President. By the age of nine, I pretty much gave up any idea of ever even surviving the age of 21 because I felt so completely alienated. I probably alienated myself more than the other way round. I was always trying find someone who liked art or music, but it was always sport."

MTV'S ONLY HIGHLIGHT BEGINS its nightly slot. Beavis & Butthead is a colour cartoon which surpasses the dorky humour of Wayne's World. It's all about anti-social behaviour and bad manners, as exemplified by tasteless metalhead adolescents Beavis (in the Metallica T-shirt) and his bosom buddy Butthead (who favours AC/DC). Everything is "cool, dude", they shop at Babes R Us, strum air guitars, talk over rock videos (including Nirvana's) and massacre them. They're super ugly and they don't give a shit. The major cringe factor comes with their sick Muttley laughs. Kurt, who earlier dismissed MTV as "an advertisement station", turns the volume up. "I have to admit, I like this. I think I've seen every episode."