The belfry went up around 1307, on the main market square, when Kortrijk - then usually written Courtray - was prospering on the back of Flemish cloth. The town's wealth was its looms, and the looms needed a clock. The bell tower kept the rhythm of the working day, signalling fire, alarm, the start and end of shifts, the death of a magistrate, the announcement of a treaty. The original tower was taller, but it had stability problems, and the upper section was shortened and crowned with a lower spire flanked by four small corner spires. That silhouette is the one you see today, though it now leans a measurable amount to the west, the way old Flemish towers tend to in soft river clay.

For most of its life the belfry was not freestanding. It was the main tower of the city's Cloth Hall, built in 1410, a long arcaded building where wool merchants stored bales and conducted business. When that hall became too small in the 15th century, a larger one went up on what is now Theatre Square, and the old halls were turned into twenty-two small houses with a shared courtyard - a small medieval co-op that lasted, in various forms, until the late 19th century. In 1896 the city authorities, in the name of urban hygiene and traffic flow, bought up the houses and tore them down. The belfry was supposed to come down too. It blocked the sightline toward Tournai Street. Citizens protested. The architect Joseph Viérin restored it. The tower stayed.

Look up. The golden figure on top of the spire is not a saint. It is Mercury, the Roman god of merchants and thieves and travellers - which Kortrijk's wool traders evidently saw as a single category. He was added in 1712 and carries his caduceus and his winged hat above a city that has always lived by trade. On the frontispiece below, the city's coat of arms shares space with a statue of the Virgin, the two patrons of a working town: commerce in front of God, or God in front of commerce, depending on which window you look out of. The Second World War nicked the belfry but did not destroy it. A proper restoration in the 1950s put it right again.

On 27 November 1382, a French army crushed a Flemish uprising at the Battle of Westrozebeke, about 25 kilometres north of Kortrijk. Some 26,000 Flemings died, along with their leader Philip van Artevelde. Among the punishments inflicted on Kortrijk afterwards was the removal of the city's bell jacks - Manten the man and Kalle the woman, cast figures whose job was to strike the bell. They were carted off to Dijon, Burgundy's capital, where they served a duchy for centuries. In 1961, after restoration of the belfry was largely complete, the sculptor Victor Cassiman cast new ones, and Manten and Kalle came home in modern bronze. They mark the hours now. Children point at them. Locals dress them for Christmas. A city that lost something in 1382 made it again in 1961, which is, in its way, what European towns do.

Unlike most of Belgium's UNESCO belfries, this one is free. A narrow steep staircase, open to the public without charge, leads up past the carillon's clock chamber and out toward the leaning crown. In 1999 the belfry was added to the World Heritage List as one of the Belfries of Belgium and France - fifty-six towers across two countries, recognised not as religious buildings but as civic ones. The point of a belfry, UNESCO's citation notes, is that it does not belong to a bishop or a king. It belongs to the town. A carillonneur plays from a hand keyboard on Sundays, holidays, and market days. In summer there are concerts. The 16th-century carillon was replaced again in 1994. The bells, like the towns that rang them, have been recast many times.