Maastricht is the centre and the reason the rest of the region works. The city sits on the Meuse in the bend where the river turns north, founded by the Romans as Mosae Trajectum — the Meuse crossing — and Christianised in 384 by Saint Servatius, who became the city's patron and whose tomb in the basilica draws pilgrims still. The street pattern carries the layers visibly: a Roman road grid in the Stokstraat district, a medieval wall surviving as the Helpoort (the oldest remaining city gate in the Netherlands), Spanish-era bastions buried under nineteenth-century park ring, and post-war housing pushed out toward the airport. The city's Burgundian self-image — wine and cheese, eight Michelin stars in a twenty-kilometre square, fine antiques and the TEFAF art fair every spring — is partly accurate, partly a marketing campaign that has gone unrebutted for decades. Either way, it works.

The geology runs to limestone and the soft yellow marl called mergel. South Limburg is where you can build a wall, a barn, an entire castle out of the local rock; where the same rock has been dug out from underneath for two thousand years; where the cave systems left behind by quarrying twist for kilometres under the surface. The casemates of Maastricht are one famous example — tunnels cut into Sint-Pietersberg as part of the city's defences, and during the Second World War the storage vault for Rembrandt's Night Watch and other masterpieces evacuated from Amsterdam. The Valkenburg caves are another: underground rooms transformed by enterprising operators into a full-scale replica of Roman catacombs, a Christmas market every December, and tourist trails year-round. Even modest South Limburg villages have houses with marl-lined cellars that connect, sometimes, to passages no one in the family remembers digging.

The official tourist itinerary through the rolling country is the Mergelland Route — 110 kilometres for cars, 125 for cyclists, marked end to end by the ANWB. It loops between Vaals and the Belgian border villages, between Valkenburg's castle ruins and Schaloen's moated marl walls, past the timber-framed vakwerkhuizen — white or yellow houses laced with black structural beams — that look transplanted from Bavaria. The area between Vaals and Gulpen has been voted the country's most beautiful natural region. The Night of Gulpen, a seventy-kilometre overnight hike, draws hikers who want their walking accompanied by a strict edge of physical commitment. On any weekend in summer the trails are full. The Limburgish dialect spoken by people you pass slides toward German near Vaals and toward Dutch near Maastricht; cross any border and people on the far side speak versions of the same dialect, and understand each other better than they would understand standard Dutch.

The South Limburg economy of the twentieth century was coal. From around 1900 to the mid-1960s, mines around Heerlen, Kerkrade and Brunssum employed up to fifteen percent of the regional population — some directly underground, more in transport, services and the long tail of pit-village life. The first mine in the region was opened by the monks of Rolduc in the twelfth century at a place that became Kerkrade. By the 1960s, cheaper foreign coal and Dutch natural gas killed the industry. The mines closed. The unemployment that followed was severe and is part of why South Limburg now has more European-funded development plaques than anywhere else in the country. Heerlen's Thermenmuseum sits on Roman bathhouse foundations and explicitly pivots the city's identity back toward something older than coal. Kerkrade's Continium science centre points it forward.

The food and the festivals declare the region's affinities. Carnival, celebrated wildly in the week before Lent, is a Catholic Rhineland tradition; the rest of the Netherlands largely ignores it. Limburgse vlaai — a fruit or pudding tart on a yeast-dough base, regional varieties almost a religion — appears at every birthday and church coffee in the province. Zuurvlees is the local stew, sweet and sour, traditionally made with horse meat or beef and served with fries; visitors order it suspicious and finish it converted. Nonnevotten, deep-fried pastry knots, came out of the carnival kitchens and are now sold all year. The sweetness in the cooking, the story goes, came down from Liège, the Belgian patisserie city where young Limburg cooks once trained. The breweries — Brand at Wijlre, Gulpener at Gulpen, Leeuw at Valkenburg, Alfa at Thull — fill the bars of the region with beers that get to the rest of the country only sometimes. Wine is newer: Apostelhoeve, the largest Dutch vineyard, sits just outside Maastricht, and Château Neercanne grows the only wine in the Netherlands that is allowed to call itself Château.

Ten kilometres east of Maastricht, on the road that has run from the city to Aachen since Roman times, lie 8,301 white crosses and Stars of David. The Netherlands American Cemetery and Memorial at Margraten holds American servicemen killed in this region in the Second World War, with another 1,722 names of the missing engraved on the Walls of the Missing. South Limburg was the first Dutch territory liberated in September 1944, by men who had landed in Normandy ninety days earlier. Some of the dead at Margraten died crossing the very Meuse that runs through Maastricht; some died in the Battle of the Bulge, fifty kilometres south. Local Dutch families have, for eighty years, adopted individual graves and put flowers on them. The custom continues, generation after generation, in a quiet ritual that the American visitors who come every Memorial Day still find difficult to talk about.

South Limburg's tourism brochures treat Aachen as if it were part of the region, because in every practical sense it is. The German imperial city, where Charlemagne held court and was crowned, sits eight kilometres east of Vaals; you reach it by bus from Heerlen or Maastricht. The cathedral, the spa baths, the Christmas market — they are part of the rhythm of the year on this side of the border too. Liège is similarly close to the south, reachable by direct train from Maastricht in under half an hour. The Meuse-Rhine Euroregion that the South Limburg administration has spent decades building is real. A South Limburg teenager can grow up in three countries' radio range, with grandparents in each, and find this completely ordinary. The Dutchness of the place is the thinnest of its many layers — the one most recently arrived, and the one with the loosest grip.