The order matters. Miners were cutting into the Rammelsberg, the hill on the northern rim of the Harz just south of the walls, long before there was a Goslar to speak of; the town first appears in a deed of Emperor Otto II in 979. In 1005 Henry II built his imperial palace at the foot of the hill, and the settlement that grew around it made armour and struck coin from metal that arrived by cart from a few hundred metres away.

Local legend gives the credit to a horse. A knight called Ramm, in Otto the Great's service, is supposed to have tied his mount halfway up the hill while he went hunting; the animal pawed at the ground and scraped open a ledge of silver rich enough to keep miners busy for a thousand years. The hill took the knight's name and the town took his wife's, Gosa. It is a good story. The mine, at least, is real: it worked without a break until 30 June 1988.

Goslar's central problem was thirty metres of geography. As a Free Imperial City it answered directly to the emperor, with no regional lord standing over it, and since emperors had better things to do than sit in Goslar, the burghers mostly ran their own affairs. But the city's liberties stopped at its walls — and the mine that everything depended on lay just outside them, in country the Dukes of Brunswick claimed.

So the craftsmen of a self-governing imperial city had to lease access to their own economy from a feudal neighbour who would happily have swallowed the town whole. The arrangement produced exactly the friction you would expect: raids, sieges, generations of grinding dispute between the dukes' men and the burghers. It was not settled until the Goslar Accord of 1642, six years before the Thirty Years' War itself ended. Goslar's imperial status outlasted the quarrel by another century and a half, until Prussian troops annexed the town in 1802.

The old town is a lesson in how a wealthy German town built itself, storey by storey. Beams are carved and painted at eye level where the money showed; upper walls are hung with grey Harz slate in overlapping scales against the weather. Rosettes, fan patterns and inscriptions run along the sill beams, and the upper floors jetty out over the street a few inches at a time.

The set pieces are worth finding. The Marktkirche of St Cosmas and St Damian dates from around 1151. The Kaiserworth on the market square was raised in 1494 by the cloth merchants, who put their guildhall next door to a town hall that had only just been finished — a piece of civic one-upmanship that has housed a hotel for nearly two hundred years. The Breites Tor and the surviving Zwinger tower show what the ramparts were once like, with walls thick enough to shrug off sixteenth-century artillery. Goslar had its darker civic business too: by the town's own account, the last witch was burned here in 1657.

UNESCO inscribed the Mines of Rammelsberg and the Historic Town of Goslar together in 1992, and extended the listing in 2010 to take in the Upper Harz Water Management System — the ponds, ditches and tunnels that miners dug over centuries to move water onto wheels. The pairing is the point. The town is not a picturesque survival that happens to sit beside an old mine; it is the mine's balance sheet, converted into oak and stone.

Today about 47,000 people live in the municipality, which sprawls well beyond the medieval core into the Harz itself. The Brocken, at 1,141 m the highest ground in northern Germany, stands about 16 km to the south-east, and the forest tracks and ponds behind the town see more walkers than the market square sees tourists.

For a town whose great age ended around 1500, Goslar has an unexpectedly sharp modern habit. Since 1975 it has awarded the Kaiserring — the Imperial Ring — annually to an international artist, and the award has become the anchor of the town's festival calendar. Henry Moore received it in the first year and named a bronze after the town in return. The Goslar Warrior has stood in the palace gardens ever since, a fallen figure on the grass below walls that were old when Moore's own country was still speaking Anglo-Saxon.

It is a fitting arrangement for a place that has spent its whole existence hosting people who were passing through: emperors, dukes, ore carters, miners, and now a steady traffic of walkers who come off the Harz trails in the late afternoon and find that the town they have wandered into is nine hundred years older than it looks like it has any right to be.