Long before coal, there was the road. The Romans built Coriovallum here as a military settlement at the intersection of two arteries of the empire: Boulogne-sur-Mer to Cologne running east-west, and Xanten through Aachen down to Trier running north-south. A traveller could stop, change horses, bathe. The bathhouse is the proof. Discovered in 1940 and now sheltered beneath the Thermenmuseum that opened over it in 1977, the Thermae complex is one of only a handful of Roman bathhouses found anywhere in the Netherlands. It tells you that Coriovallum mattered, that this was not a frontier outpost but a place where soldiers and merchants soaked off the dust of the imperial roads. Then, sometime in the third or fourth century, the Romans pulled back and the town faded for six hundred years.

Heerlen reappears in the historical record in 1065, listed in a document by Udo, bishop of Toul, as a possession in the bishopric of Liege. The counts of Are arrived, built a moated castle and the Schelmentoren prison tower and the Romanesque Saint Pancratius church whose 12th-century stones still stand in the town centre, and Heerlen became the head of the Land van Herle, with surrounding villages falling under its legislation. For the next seven centuries, history happened to Heerlen rather than because of it. Dukes of Brabant claimed it in 1244. Spanish and Dutch Protestant armies swapped it back and forth through the Eighty Years' War. The 1661 Partage Treaty parked it in the awkward little wedge of Dutch territory poking into Spanish Netherlands, isolated, agrarian, easy to overlook.

Coal had been found at the Valkenburgerweg in 1874, but for a quarter-century almost nothing happened. Setting up a mine took capital and patience that private enterprise did not have. In 1901 the Dutch state intervened, bought up the unsold concessions, and chartered the Staatsmijnen - the State Mines - that would become DSM. The transformation was almost violent. In 1900 Heerlen had 6,646 inhabitants. By 1910 it had 12,098. By 1930, it had 32,263. The old town centre was demolished to make way for shops and offices and the housing that thousands of new miners needed. Slag heaps grew on the horizon. A whole regional culture, in dialects that mixed Dutch, German and the patois of the pits, organized itself around the rhythm of the shifts. The miners shopped at Schunck. They sent their children to Catholic schools. They knew Lange Jan and Lange Lies the way other people know cathedral spires.

Then it ended, almost as fast as it had begun. Cheaper coal from Poland and the United States, then the discovery of natural gas in Groningen in 1959, made the southern Limburg mines uneconomic. The last shaft closed in 1974. The Dutch government tried to soften the blow by relocating large state agencies - the pension fund ABP, the statistics bureau CBS - to Heerlen, but a desk job in an office is not the same kind of work as a shift underground, and the social and cultural rupture cut deeper than the unemployment numbers. The slag heaps were levelled or planted over in a programme called van zwart naar groen, from black to green. Lange Lies and Lange Jan came down. Today only one mining building remains in the city itself: shaft 2 of Oranje Nassau I, now the Dutch Mine Museum. Walk through Heerlen looking for the industry that once defined it and you will struggle to find it.

The hopeful object in this story is a department store. In 1935, in the depths of the Great Depression, the textile merchant Peter Schunck commissioned the young Heerlen architect Frits Peutz to design a new store next to the medieval Pancratius church. What Peutz delivered was the Glaspaleis - eight floors of steel and concrete wrapped in a free-standing glass curtain, an extraordinary leap of early Modernism that nobody quite knew what to do with. For decades it was abused and altered and nearly demolished. Then in the 1990s the International Union of Architects placed it on its list of the thousand most important buildings of the 20th century, one of only thirteen Dutch entries. The city bought the dilapidated building, restored it, and filled it with a museum of modern art, a library, a music school. The Glaspaleis is now what Heerlen is most often photographed for, and that is fitting: the city built around a vanished industry has chosen, as its symbol, the building that promised the next thing was possible.