"We're a small city on a small island on the edge of Europe," says Paul Donnelly. "How did this happen to us?"
Our multi-cultural party – northern European, North Americans, young Asians and antipodeans – are gathered at Belfast's elegant City Hall (once a prime bombers' target) for a three-hour history-of-terror walk around Northern Ireland's capital.
"This isn't a typical city tour," Donnelly warns us. "It's a human tragedy, with real victims."
We never discover whether Donnelly is Catholic or Protestant, such is his balanced commentary. But his first personal encounter with sectarian terrorism came at primary school.
Asleep in bed, his family's terraced home was shaken by a bomb. Before that night, Catholics and Protestants lived "cheek by jowl", Donnelly says.
Next morning, "my father boarded up the house", and the family moved to a safer inner city suburb – one defined by religious allegiance.
If the hapless Brexit discussions bore you senseless, and the "backstop" sounds like something you might suffer after drinking one Guinness too many, consider why few Irish – either side of the border – want to reignite the civil war known as "The Troubles".
Our hotel, the Europa, still holds the record for being "the most bombed hotel in the world" (something not mentioned on its website).
Between 1968 and the Good Friday Agreement of 1998, it was bombed 33 times by the Irish Republican Army (IRA) – a ripe target because the international media stayed here, guaranteeing worldwide coverage.
Today both the Europa and Belfast are enjoying a tourism renaissance. A record 117 cruise ships visited Belfast last year.
The city's Titanic Museum remains a world-class attraction, Northern Ireland cuisine is booming, and Belfast has become one of Britain's most rapidly growing tourism destinations.
But during the Troubles, Donnelly explains, this same city centre was a no-go area protected by the British Army's notorious "Ring of Steel".
"Imagine going through modern airport security checks just to go to the supermarket," Donnelly says at the site of one former checkpoint. "Prams had to be searched, because women were smuggling armaments under sleeping babies."
Most of the three-kilometre walking tour requires imagination. Most of the buildings Donnelly describes were destroyed, by one side or the other.
The first stop, in Donegal Place, is now a ubiquitous High Street brand. "This was the former site of the Celebrity Club," Donnelly explains. In October 1971, the Celebrity was where young Protestants and Catholics mixed to enjoy the music.
"Then a blue Ford Cortina pulled up," Donnelly continues.
Four teenage IRA supporters were inside. Three emerged, including Martin Forsythe and Patricia Murray, leaving their getaway driver to whisk them away once they had placed their bomb at the lift – the club's only entrance and exit.
After they'd held the security guards hostage and primed the bomb, the teenage terrorists found the lift opening to reveal two men – undercover cops from the hated Royal Ulster Constabulary.
The cops fired. Murray, permanently paralysed, was never charged (and later ran a book shop). Forsythe was shot dead in the road.
Our next stop, in Castle Lane, places us outside the former site of the Abercorn restaurant and bar.
Saturday, March 4, 1972, was busy, Donnelly explains. The Abercorn, owned by Catholic Bill O'Hara, was a popular place for families to enjoy a post-shopping meal, with a bar upstairs.
At 4.28pm the police received a warning. Two minutes later the bomb went off. Sisters Rosaleen and Jennifer McNern were planning Rosaleen's marriage. Both lost their legs: the bride also lost her right arm and an eye.
"There's no plaque to commemorate the atrocity which happened here," Donnelly says. "But how can you register the atrocities committed in Belfast? It would be commemoration saturation."
Next Donnelly pauses in front of what used to be Mooney's bar in Cornmarket. Celebrated for its Galway oysters, excellent Guinness and live music, Mooney's was an off-duty haunt of British "squaddies".
Two Irishwomen "entrapped" three teenage Scottish soldiers here in 1971, inviting them to "a party". The squaddies' bodies were later found on the moors.
If the tour seems weighted against the IRA, it's only an accident of Belfast's geography. Donnelly soon launches into a denunciation of equally murderous Protestant kill squads.
The Ulster Volunteer Force (UVF), was responsible for terrible war crimes. But it, in turn, was usurped by the more extreme Ulster Defence Association (UDA), the largest loyalist paramilitary group in Ulster whose members patrolled the Protestant estates either side of the Shankill Road.
They were followed by the Ulster Freedom Fighters (UFF) – and worst of all, "the Shankill Butchers": a group who murdered and extorted for criminal private gain.
Donnelly's tour concludes at Belfast's beautifully restored Lagan riverfront by the city's Concert Hall.Opened in 1997 by Prince Charles, the concert hall is particularly poignant because his mentor, Lord Mountbatten, was assassinated by a bomb planted by the IRA as he went to take his twin teenage grandsons lobster potting in the Republic in 1979.
Apart from Mountbatten and his grandsons, 19 others died – including a teenage deckhand born and bred in the Republic.
In 2012 the Queen shook hands with the late Martin McGuinness – the former IRA commander complicit in Mountbatten's execution.
For 20 years, the Good Friday agreement was a shining beacon to the rest of the world's trouble spots that peace is always an option.
Let's hope it survives the Brexit negotiations.
DC Tours offers three walking tours of Belfast, see deadcentretours.com
Cathay Pacific flies from Australia to Dublin four times a week, via Hong Kong. See cathaypacific.com.
Belfast is a three-hour car journey from Dublin airport.
Europa Hotel. See hastingshotels.com/europa-belfast.