BELFAST, NORTHERN IRELAND—There is an everyday quality to the reminders of conflict in Belfast. Divis Tower is an ordinary apartment building by most measures. But during Northern Ireland’s three-decade sectarian conflict between Protestants wishing to remain part of the United Kingdom and Catholics seeking union with Ireland, the British Army occupied its top two floors. The unremarkable 20-story structure, which rises over the divide between the deeply Catholic Falls Road community and the Protestant neighborhood along Shankill Road, has overlooked some of the city’s most brutal violence.

Today, the upper floors have been turned back into housing—a step toward normal. But what does “normal” mean in a city recovering from conflict? Peacetime cities are prone to flux, becoming new versions of themselves as populations and neighborhoods change in ways that redefine daily life over time. In post-conflict cities, like Belfast or Mostar or Beirut, this reinvention of normalcy also incorporates the physical and emotional remnants of war.

This pattern is visible in Belfast nearly 17 years after the Good Friday Agreement put an end, at least formally, to Northern Ireland’s conflict. Many of the city’s Catholic and Protestant neighborhoods remain isolated from one another, in some cases with physical barriers. The late David Ervine, a Protestant fighter turned politician in Belfast, once said of his divided community:

Each side presumes that the other side doesn’t live a normal life. The other side lives a life that is calculating, unreasonable and evil towards us. Whereas the vast majority of people on the other side get up in the morning, hope they have a job, go to their work, raise their kids, do the things that normal people do in abnormal circumstances. But if the abnormality lasts long enough, the abnormality itself becomes normal.

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The period known as the Troubles defies easy explanation. The name makes it sound more like an inconvenience than what it really was: a long battle between mainly Catholic Irish nationalists and mainly Protestant British loyalists that took thousands of lives between 1969 and 1998. The roots of that fighting predate by centuries the 1921 partition of the island into a British-controlled north and an Irish-governed south. But in the late 1960s, Northern Ireland’s Catholics staged protests against the discrimination they faced in housing, voting, and employment. Demonstrations were met with crackdowns, rallies with retaliations. Paramilitary organizations like the Catholic nationalist Provisional Irish Republican Army (known as the IRA or the Provos), and Protestant counterparts like the Ulster Volunteer Force (UVF) and the Ulster Defense Association (UDA), fought each other in the name of protecting their communities as well as for revenge, killing civilians in the process. In response, the British government enforced draconian counterterrorism policies, detaining paramilitary fighters without charge and torturing prisoners.

This history was long past by the time I visited Belfast, the capital of Northern Ireland and a focal point of the fighting, last year. The Good Friday Agreement had among other things called for power-sharing among the main Protestant and Catholic parties, as well as the “normalization” or demilitarization of the police into an ordinary arm of law enforcement rather than an army at war. But I wanted to see how the Troubles still intruded on the city.

Today, life in Belfast occurs amid structures, relics, and habits that have outlived the Troubles. The taxi services, for example, have a past as getaway cars, body-moving vehicles, and free transportation for mourners traveling to funerals. Now, in addition to performing their regular cab duties, drivers give tours of Belfast's still-divided working-class communities. Barriers of concrete, barbed wire, and corrugated iron known as peace walls physically separate Protestant from Catholic neighborhoods, and I learned about their history from a cab driver who had grown up nearby, surrounded by the violence.

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My driver, a Falls Road Catholic, kept a £1 pocket history of Ireland in the seat beside him, along with a map he said needed replacing. Parked in an out-of-the-way spot on a residential West Belfast street, he passed a book of black-and-white photographs back to me. With a sense of rhetorical justice simultaneously rehearsed and genuine, he promised to give both sides equal treatment in the tour, perhaps in a self-aware effort to smooth the rough surfaces of Belfast's history and move on to something more open-minded and academic.

This kind of Troubles tourism is routine for the city. "It is part of life here," Neil Jarman, a researcher at Queen's University Belfast and the director of the Institute for Conflict Research, told me. Jarman moved to Belfast from England a quarter century ago for research and said the only way he could get to know the city’s patterns of segregation was to walk through its neighborhoods. Nor is conflict tourism unique to Belfast. Many sites of trauma are open to visitors, from New York’s 9/11 Memorial Museum to Hiroshima's Peace Memorial Park and the Auschwitz-Birkenau concentration camp. In Romania, tourists can visit the military base near the town of Targoviste where former dictator Nicolae Ceausescu and his wife were executed by firing squad.

Torie Rose DeGhett/The Atlantic

In Belfast, however, many sites aren't maintained with tourism in mind, and Jarman doesn't think they ever will be. That's not their purpose. The much-visited walls remain because the city's peace is still a process, and some residents continue to fear they would be attacked if the barriers came down. The largest of these, a structure of concrete topped with mesh and metal sheeting that rises 30 feet above Cupar Way, was erected to separate the Catholic-inhabited Clonard from Protestant-dominated Shankill following fiery clashes between those communities in August 1969. The wall was supposed to be temporary. Instead, it has simply grown in size, and dozens more have been constructed, some even since the end of the Troubles. According to the Belfast Interface Project, which researches the city’s divided communities, seven new barriers have been built since 2000—a testament to the enduring specter of sectarianism.

The peace walls are a manifestation of Belfast's struggle with the idea of normalcy. "They're largely seen as an aberration, as an example of how not normal Northern Ireland is," said Jarman. "And I think, for a lot of people, they want to move on and become normal, rather than living with the aberrations."

Similarly, Belfast’s famous murals were not painted to preserve history or attract tourists, but because their messages reflect the sentiments of the communities surrounding them. This is visible in the ways they have changed, or not changed, along with the peace process. Jarman told me that following the IRA’s 1994 ceasefire and the Good Friday Agreement, images of gunmen largely disappeared from the walls of Catholic neighborhoods. The murals along Falls Road, for example, form a patchwork of tributes and political messages, some honoring symbolic IRA figures and others expressing solidarity with causes like Catalan independence and Palestinian statehood. But images of gunmen remain prominent in Protestant neighborhoods. “In nationalist areas,” Jarman said, “you see more relevance to politics and current affairs. In loyalist areas, you see representations of victimhood.”

Solidarity murals in West Belfast (Torie Rose DeGhett/The Atlantic)

Some parts of the city, however, are preserved specifically for visitors, as if to organize the past into something archived and comprehensible. It was not even two decades ago that Crumlin Road Jail housed fighters from paramilitary organizations on both sides of the sectarian divide; it has since closed and reopened as a museum. At one point it was home to some of the most recognizable names of the Troubles. Among them was nationalist icon Bobby Sands, who spent about two months at Crumlin before being transferred to another jail, where he was the first of 10 prisoners to die in a hunger strike. Some of Northern Ireland’s top-ranking politicians today served time there as well. But the building now hosts concerts, including Elvis and AC/DC tributes. You can even get married there.

The prison’s legacy of sectarian fighting, executions, shootouts, and jailbreaks is now the stuff of guided tours. After a walk down the length of the C wing, my tour group and I ended up at the execution chamber, complete with an authentic noose. The guide said he wasn’t sure whether that specific rope had ever been used to kill anyone, but other nooses like it took the lives of more than a dozen prisoners until the jail’s last execution in 1961. Most of those men are still buried in unconsecrated earth on a corner of the prison grounds, their graves the last stop on the museum tour.

Across the street from the jail, the Crumlin Road Courthouse, where the prisoners underwent hearings, has not been restored and preserved like its neighbor. It was closed after the Good Friday Agreement and later sold to a developer, who planned to turn it into a hotel or office building. Instead, the building has fallen prey to a series of arson attacks, and its façade hides a burned-out shell. The courthouse is a visual counterpoint to the jail, a reminder of the difficulty of smoothly bridging the traumas and damages of the past to the hopes and tensions of the present.

On my cab tour, the driver and I passed through a set of security gates at North Howard Street, which connects Falls Road to the Shankill area. The gates allow traffic through unimpeded during the day but close off the route in the evening—Belfast isn’t ready to keep them open 24 hours a day. Crossing through them was in a way like leaving one world and entering another. In the neighborhood behind us, the Irish tricolor decorated murals mourning Bobby Sands. In the one we were entering, the Union Jack was displayed near imagery of the UVF and the Queen. Back there, in spirit at least, was Ireland. In front of us was Britain.

Shankill was the second part of the tour, a trip through unmistakably Protestant territory. We passed by commemorations of lives lost in IRA attacks and an intimidating mural of smiling gunmen. The tour concluded in front of a majestically painted mural of the Protestant hero King William of Orange, who defeated the deposed Catholic King James II in July of 1690 in the Battle of the Boyne, solidifying what would become centuries of Protestant domination of Ireland. The roots of the Troubles run deep.

Elsewhere, physical links to the Troubles—snipers’ perches, British Army bases, and barbed wire—have been disappearing for more than a decade. During the Troubles, the Belfast city center, which saw roughly 70 conflict-related deaths, was surrounded by a threatening constellation of railings and police checkpoints known as the “ring of steel.” In the early 1990s, Belfast reporter David McKittrick described the tense atmosphere of flak-jacketed policemen and restricted roadways. "For local people," he wrote, "familiarity has bred acceptance and the abnormal is now accepted as the norm." But downtown Belfast now operates as neutral space, the shadow of the Troubles pushed out by restaurants, hotels, and a tourism office. In contrast to the working-class neighborhoods just beyond it, where the conflict’s painful history is marked street by street, the city center has no tributes or memorials of the conflict. "There's no remnants of it. There's no legacy of it. It's not mapped, it's not recorded anywhere," said Jarman.

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Normal is a political term in Northern Ireland's recent history. Decades before the Good Friday Agreement’s “normalization” provisions aimed at demilitarizing the police, the British embraced an idea that went by the same name, to treat Northern Ireland’s paramilitary groups more like common criminals than armed political adversaries. In 1976, British Home Secretary Merlyn Rees said paramilitary prisoners would no longer be part of a “special category” of prisoners enjoying certain privileges. That announcement ultimately led to the prison hunger strikes in which Bobby Sands and nine others died. This was when Northern Ireland hurtled into what journalist Ed Moloney called "the darkest period of the Troubles," with sectarian killings escalating in both numbers and brutality. Anything but normal.

Today in Belfast, normal can mean putting fresh coats of paint on old grievances so they can be relived again and again. Sometimes that’s literal, as in the case of murals; sometimes the revival of familiar anger comes during summer marches by Protestant communities celebrating the long-ago victory of William of Orange. Other times attempting normal means polishing smooth the serrated edges of history, as museum guides do when they lead tour groups through jail cells.

Belfast’s efforts to put the Troubles behind it are challenged by the endurance of old barriers and enmities. Past and present duel with each other there—the inevitable passage of time and the desire to move on are in tension with long memories of pain and injustice for which there are still plenty of reminders. On Dunville Street, just off the Falls Road, half a mural peers out from between two brick houses. It is mostly scraped away, and a newer building has gone up in front of it. Its central proclamation remains: "25 Years of Resistance ... And 25 more if needs be!" Murals come and go in Belfast, but this one exists in limbo as the ghost of a threat, living half in and half out of the Troubles.