Genesis in concert at Twickenham Stadium, London in 2007
"They say there were 500,000 at the concert, but to honest, if you were in Rome that night, you were there... you had no choice," said Phil Collins, Genesis drummer, singer and greatest showman.
"I've got a friend who works in The Vatican - which is a mile or so away across the river - and he told me that it was pretty loud even over there and that everyone opened their windows to let the music in."
The vast show - the biggest on their first tour for more than 15 years - attracted die-hard Genesis fans from all over the world, much to Collins's surprise and eventual consternation.
"I'd spent the whole day learning a few Italian phrases phonetically," he added with a rueful grin.
"But after the first couple of songs, I started talking to the crowd and it was like the first ten rows had question marks over their heads.
"They didn't have a clue what I was talking about because they couldn't understand Italian - let alone my bad Italian!"
Despite the fact that the Rome concert was the last on the band's 22-date European tour, all three band members - Collins, guitarist Mike Rutherford and keyboards player Tony Banks - admit to having had last-minute nerves.
It wasn't the setting amid the picturesque ruins of the hippodrome where Julius Caesar presided over chariot races, nor the almost unimaginable size of the crowd in front of them, but the fact that the concert was being filmed and that they had only "one take" to get everything right, explained Collins.
"We had put a lot of work into rehearsing, putting the show together and playing live for the first time in 15 years and we wanted it to be right.
Genesis: Tony Banks, Phil Collins and Mike Rutherford
"In the end, there was a great feeling because it was a free concert and everything went pretty much according to plan.
"Although I think we all agree that it wasn't our absolute best performance. There was too much at stake."
Last week, Genesis released a lavish new DVD, When in Rome 2007, featuring the Rome show in its entirety, together with a revealing behind-the-scenes documentary of the entire tour.
To coincide with the film, The Mail on Sunday will next week give away a specially commissioned CD of Genesis music, including Turn It On Again, Follow You, Follow Me, Mama, Abacab among many others.
The track listing was selected by Tony Banks who, along with Mike Rutherford and former lead singer Peter Gabriel, founded the band at Charterhouse School 40 years ago.
"In the early days, Genesis was best known as a live band - so we wanted to give people the opportunity to hear what we sounded like on last year's tour," said Banks.
"But other songs, such as The Cinema Show (from 1973's Selling England by the Pound) have been remastered from the original tapes.
"Modern technology such as "surround sound" gives us the opportunity to make them sound so much better.
"I also took the opportunity to sneak on a favourite song of mine, Many Too Many, which rarely sees the light of day," he added.
The song, from the 1978 album And Then There Were Three, was written by Banks himself.
Banks, 58, and Rutherford, 57, became the effective guardians of the Genesis legacy after Gabriel went solo in 1976 and Collins left in 1993.
It is they who have masterminded the gradual re-packaging and re-releasing of their back catalogue over the past year to keep track with the latest advances in technology.
And they who nurtured the idea of taking Genesis's famously theatrical and spectacular stage show back on the road after a hiatus of 15 years.
Unlike many of the slew of more recent bands who have re-formed in an attempt to revitalise their fading fame and dwindling fortunes, neither Banks and Rutherford nor 57-year-old Phil Collins need the cash or the exposure.
Genesis have sold in excess of 150million records worldwide and live enviable lives of comfortable, moneyed leisure.
"The reason we got back together was that we all thought it would be fun," said Rutherford.
"We all get on tremendously well together and I think we all had a sort of nostalgia about getting together, going on the road and playing our music.
"It's what being in a band always used to be about.
"A lot of bands split up because they can't stand the sight of each other any more, but we stopped playing together because we - particularly Phil - had other things going on in our lives."
Rutherford, who lives in Sussex, is an accomplished polo player, countryman and horse lover.
His near-neighbour Tony Banks's consuming passions are his eight-acre garden in Surrey and composing music - he is currently working on a follow-up to his successful 2004 classical suite Seven.
Meanwhile Phil Collins lives near Geneva to be close to his two young sons Nicholas, seven, and Mathew, three, from his third marriage to Orianne Cevey, which ended two years ago.
"I've stopped touring and performing now because any time I spend away working, I am away from my family," he said.
"When I have the boys, I'm busy with them. But when they are not there, I spend most of my time in the basement where I'm building a model railway, though to be honest, it's making the scenery that fascinates me."
Five members of Genesis - including Peter Gabriel and guitarist Steve Hackett - began discussing doing a live version of their classic 1974 concept album The Lamb Lies Down On Broadway three years ago.
But Gabriel - who famously laboured for a decade over his last album - said he needed to complete his latest record, which even now has no release date.
"So eventually Phil, Tony and I decided that we would go ahead it without him," explained Rutherford.
"We also decided it would have to be a different kind of tour, performing later material which Phil originally sang on.
"I think all of us were glad we did it - playing together was enormously good fun - although I don't think any of us realised quite what hard work it would be."
Part of the problem, of course, was the ravages of age.
Rutherford was recovering from severed tendons in his left hand, which threatened his guitar playing.
Phil Collins, whose powerful drumming set the style for a generation - not to mention for the animated gorilla in last year's Cadbury's commercial - appeared to have forgotten how to play the drums.
"Well, I don't really do that any more," he confessed. "Until we started rehearsing, I hadn't played the drums properly in years.
"We booked a rehearsal space in New York and with a bit of practice it soon came back. But more importantly, I had also forgotten what good friends we were and how long we had been together.
The way they were: The band (from left, Peter Gabriel, Tony Banks, Phil Collins, Steve Hackett, Mike Rutherford) pictured in Copenhagen, Denmark, in 1975
"A lot of the albums we made were written together, with just the three of us sitting in a room and jamming - sometimes for weeks - until we came up with something we could record.
"We'd often go on tour for a year at a stretch. There's a special kind of chemistry that happens when we get together - and its still there."
The fabled rock 'n' roll lifestyle, though, presented no difficulties, even to a trio of gents rapidly approaching their 60s.
"We've had our moments, of course," smiled Rutherford.
"But you have to be pretty sharp to play the sort of music we play in front of a huge audience night after night.
"I don't think you could do it for as long as we have if you were too wild. That's probably why some bands burn up and fall apart after a couple of years.
"Even in the early days, we used to take our wives and girlfriends on tour with us.
"Sometimes even the children before they started school. We have a good time touring, but it's a very English good time."
All three members of the band say they were surprised at the composition of the sell-out audiences on last year's tour - they were seen by 1.5 million people in Europe and played 20 smaller gigs in the US.
"There was a real mixture of people, young people, original fans and others who might have thought this was their only chance to see us," said Collins.
"I remember in Poland looking out into the audience and seeing eight, ten-year-old kids, standing next to people in their forties and others who looked like skinheads.
"They all stood out in the rain for hours to hear us and sang along to every word.
"It was really moving to know that Genesis's music has been so important to them, particularly as we had never been there before.
"The last time we were doing big European tours, they were behind the Iron Curtain.
"The amazing thing about Genesis is that we've always been popular, even when sometimes the critics have hated us - I think we would all prefer to be loved by the fans than loved by critics.
"To us, the pleasure has been in writing the music and in playing it to the kids," said Collins.
"Though I honestly can't see us writing and recording any new music now - it's just too time-consuming.
"I'll probably always do the occasional gig and write the odd song.
"Tony will work on his music and Mike will always play guitar - he has been told by his doctor that he has to, for the sake of his tendons!
"And if the chance came up to do something live with Genesis, something different from last year's tour, then I think we'd all jump at it."
Tony Banks added: "I don't think any of us would rule out doing another tour, but it would have to be something special.
"Something like what we originally set out to do this time, performing The Lamb Lies Down On Broadway and the earlier material with Peter and Steve Hackett.
"Funnily enough, I spoke to Peter on the phone a few weeks ago and he's still not ruling it out. But when I asked him when, he just laughed. So don't hold your breath..."
© MailOnline, by Nick Pryer