24 June 1987 was no ordinary day, especially if you were a U2 fan in Northern Ireland, because it's when the band brought their Joshua Tree tour to the King's Hall in Belfast.
The Irish foursome had played the city several times during the early 1980s with their albums Boy and War - and 1984's The Unforgettable Fire had achieved critical and commercial success.
However the Joshua Tree album, inspired in part by the band's journey into the soul of America, elevated them to a different music stratosphere, with the album going on to sell over 25 million copies worldwide.
Thirty years on, a Radio Ulster programme narrated by Belfast church minister and U2 devotee, the Reverend Steve Stockman, reunites some fans who were at one of Belfast's most famous concerts.
On a cold Saturday morning in February, I persuade Geoff Caves, Brendan Mulgrew and Martin McCarney to meet me at the King's Hall.
No sooner are we standing outside what was, back then, Belfast's biggest concert venue, when memories of the U2 gig come flooding back.
"It was a bright summer's day. I'd just finished doing my A levels, actually my last A level was on that day," Brendan says.
"There were crowds of people milling around (at the King's Hall) waiting to get the best spot inside. It was the sort of feeling you don't get that often in your life and it was there that day in spades."
The concert was completely sold out but that didn't stop some fans without tickets trying to get in.
"A friend of mine didn't have a ticket. So whenever the gates at the King's Hall opened, he ran towards the main door and quickly handed a fiver to the doorman," Martin McCarney says.
Martin laughs as he recalls his mate sprinting into the venue and not being stopped, a lucky escape for one U2 fan.
It was a concert that attracted a lot of media interest and it was Ulster Television that got a real coup, just hours before the gig, when reporter Ivan Little interviewed Bono just minutes after the band's plane had touched down at Belfast International Airport.
"He told me that Belfast had a reputation, outside of Ireland, for being the best audience in the world and then he added 'that's sort of true," Ivan recalls.
"I asked him if they had any surprises in store for the King's Hall concert and he jokingly replied that the only surprise would be if they stayed in tune."
Famous support act
Of course they stayed in tune and there was another big surprise, even before U2 came on stage that night.
The band had persuaded none other than singing legend and former Velvet Underground front-man, Lou Reed, to be their support act.
After entertaining the crowds with several of his hit songs, including Walk on the Wild Side, Lou Reed made way for Bono, Larry, Adam and the Edge.
Christoph Ebbinghaus remembers the moment like it was yesterday. Now a church minister, back then as a 15-year-old this was his first concert and he was about to witness his favourite band live.
"You couldn't always make out what Bono was saying in between songs but I remember in his introduction to the concert, he described them as four friends from Dublin.
"Then he said this is the best audience in the world and we're going to give you the finest rock and roll concert this city has ever seen."
A big question being asked ahead of the King's Hall concert was whether Sunday Bloody Sunday would make it onto the set list.
One of U2's most political songs about the Troubles, the band had first played it at Belfast's Maysfield Leisure Centre in 1982.
Five years on they did play it again and, as Geoff Caves recalls, it made for one of the more memorable moments of the concert.
"There was an (Irish) tricolour and a union jack that had been pulled out during that song. Everyone who was there remembers the flag incident, Bono saying you can take down your flags, we're sick of flags," he said.
"It was quite an iconic moment. A lot of young people coming together in one place in Belfast, who wouldn't normally mix, and there was this call from Bono to take down the flags and it was obeyed."
The Rev Steve Stockman from Fitzroy Presbyterian Church in Belfast was also at the King's Hall gig.
Another memorable moment for him was in the months leading up to the concert - when U2 came to Belfast in March 1987 to launch the Joshua Tree album.
He recalls the band making a surprise midnight appearance at Makin' Tracks, a record store in the city centre.
Steve and the well known artist Colin Davidson queued to meet U2 that night and both remember the band members being "warm, friendly and interested" in meeting the fans.
With U2 set to tour again this year to celebrate the 30th anniversary of the Joshua Tree album, some of those songs that filled the King's Hall three decades ago will do so again in venues around the world.
But for many fans, including Paul Duffy, who were there on 24 June 1987 there will only ever be one unforgettable gig.
"I can't drive past the King's Hall now without thinking about that day, that fantastic evening," he said.
"I've seen loads of bands there over the years but to me, U2 and the King's Hall are synonymous with Belfast. It was just such a magical time."
The Unforgettable Gig: When U2 rocked the King's Hall airs on BBC Radio Ulster and BBC Radio Foyle at 12:30 BST on Sunday.