A murky cloud clung across the city as the bitter smell of billowing smoke lingered in the air.

It was a single spark from a faulty fuse box that would leave a "gaping wound in the heart of Edinburgh" on a cold December night 15 years ago.

At 8.11pm on December 7, 2002, smoke was spotted rising from Hastie's Close in the middle of the Old Town, a Unesco World Heritage Site.

Although the fire brigade arrived within minutes, the ferocious flames spread to several properties on the Cowgate in less than two hours.

Within four hours, the fire spread up to Chambers Street and South Bridge and it took fire crews 52 hours to fully extinguish the flames within the tightly packed streets.

Businesses such as nightclub La Belle Angele and comedy venue Gilded Balloon were destroyed in the blaze, as well as Edinburgh University's School of Informatics.

Karen Koren will never forget the highs and lows of that night.

Visiting the hospital to meet her granddaughter born that day, the Gilded Balloon owner first heard the news about the fire on her way home.

She did not realise at that point that she would never again set foot in the building where she had established her business 17 years earlier.

"That's when the newspapers started calling me," she says.

"It was devastating at the time. It was so sad because it was a bit of Edinburgh history.

"I still remember standing up at the top of Blair Street being interviewed. It was such a shock."

For George Macdonald, it was the smell coming from the blaze that will be etched in his memory of the night.

The sound engineer had been working at a show in La Belle Angele earlier in the evening and was on a break when he received a call about the fire.

He had been due to return for a second show hours later, when the nightclub would have been bustling with revellers.

"You could easily describe it as a small apocalyptic event in the centre of Edinburgh," he says.

"It was like losing a member of your family. I had probably worked around 700 or 800 nights in there. There was a big family of people involved."

Watching artists such as Radiohead, Oasis and The Libertines perform in the Cowgate venue, George says the club was a "proving ground" for many people who went on to be really successful.

He says: "There were many hundreds of really special nights in there that are in people's hearts as some of the best nights they have ever had.

"People's lives were changed by what happened in that space."

Keen photographer Miles Tubb has always been in the habit of "snapping events" of significance for his project Living Memory Association.

He remembers the moment he first heard about the news and saw the huddle of film crews and photographers at the top of Blair Street.

"I had friends who were coming out of a Christmas event on Princes Street and they saw a great plume of smoke and a light in the sky from the Cowgate area," Miles recalls.

"The scene itself put me in mind of when you see an old film of the Blitz. Great piles of rubble, smoke still rising, firemen watching the scene.

"A huge area of devastation but all calm."

The buildings destroyed by the fire were first designed in 1785.

They were originally part of a grand scheme by Robert Adam, which was deemed too costly.

Instead, a simplified version drawn up by Robert Kay in the same year was constructed.

"That was really innovative because it is very unusual to have one street built above another in that way," says Fiona MacDonald from Edinburgh World Heritage.

"Some people say it is the first urban viaduct scheme in Europe because it was very innovative. It was a huge loss to the city."

She adds: "Architecturally, it was a very complex construction so to lose that was devastating."

In 2012, archaeologists found remains from 16th century houses, such as pottery and a bone comb, after an excavation of the site.

It took more than a decade after the fire before a new development opened.

Costing £35m, a connection was made between the Cowgate, Chambers Street and South Bridge with a new hotel and shops opening in 2014.

La Belle Angele also reopened later that year after a 12-year wait.

Focusing on his record shop Underground Solu'shn after the fire, George couldn't turn down the chance of helping to bring back the club.

"When it came back, people asked me what it was like," he says.

"I said it was a bit like someone in your family who has died coming back from the dead. They are obviously a wee bit different."

Karen knew the fire would not mark the end of the Gilded Balloon.

Having opened up another venue in Teviot Row a few months before the fire, they moved all of their efforts there for the Edinburgh festivals.

Growing Teviot Row into what has now become a central hub for the Edinburgh Festival Fringe, it was not until this year the family business was able to open an all-year around venue at The Rose Theatre, the first time since being based in the Cowgate.

"The Gilded Balloon was not going to die, that was for sure," she says. "Comedians would come because it was the only place where all comedians could gather together. There was camaraderie.

"Last time I saw Steve Coogan he said he would never forget what this meant to him. We couldn't replace the spirit of the Cowgate, it was just wonderful in those days. But we had to have a fresh start and move on.

"We had supported and nurtured so many comedians and we wanted to continue doing that. And I think in many ways we have."