At the foot of the slag heaps, the industrial remains of Charleroi attract "urbex" fans.

Nicolas Buissart explains that he started his tour guide business as a joke about fifteen years ago, when a Dutch newspaper awarded Charleroi the title of ugliest city in the world.

This former design student, a connoisseur of the city, decided to capitalize on this bad reputation by launching an "urban safari", getting as close as possible to the slag heaps and giant ruins of steel and concrete that form the landscape of Charleroi.

The program varies depending on the audience.

That morning, the 46-year-old Walloon guide welcomed a group of about ten retirees from the Lille region (northern France), amateur photographers fond of the simultaneously dilapidated and graphic side of abandoned factories.

"There is an aesthetic here that I really like," Véronique Moussu, one of the group members, told AFP, this being their second visit in four years.

"These spaces are enhanced by the interplay of light, shadows and street art," the French retiree continued.

The first stop of the day is dedicated to a typical 1930s building, now disused and effectively become a playground for graffiti artists.

This is the former "Solvay swimming pool", which this Belgian industrialist had built to offer his staff a place for relaxation and leisure... Opposite a pioneering site in the manufacture of soda carbonate in the 19th century, which no longer exists.

"The waste products of capitalism"

The roof of the old swimming pool is no longer watertight, rain and wind rush into the building, and the irregularities of the tiled floor are all potential traps for ankles.

Nicolas Buissart gives his safety instructions while guiding his visitors inside, giving them half an hour to explore and photograph.

The same scenario is playing out in Châtelet, a neighboring town, in a gigantic stainless steel stripping warehouse that is also falling into ruin. The site, which was once owned by the ArcelorMittal group, has been abandoned for about fifteen years.

"Wallonia was prosperous; we are in a kind of cradle of capitalism," emphasizes Nicolas Buissart. "The problem with capitalism is that it leaves a lot of waste behind."

This hint of nostalgia on the theme of abandoned heritage also surfaces in the reactions of visitors.

"We all imagine the workers who toiled here and made these places come alive, now it's dead, it's destroyed," laments Pascale Dufour-Floor, who lives on the Franco-Belgian border and has joined the Lille retirees.

But tourism promoters want to see it as an asset.

More than forty years after the closure of the last Walloon coal mine in 1984, "this heritage of the past is a factor that differentiates us and attracts tourists," Valérie Demanet, director of the Charleroi Tourist Office, told AFP.

As for Nicolas Buissart's urban exploration safari, it complements the overall offering well. "Audiences have different expectations; there needs to be something for everyone," she adds.