Sint-Niklaas - 'Saint Nicholas,' for the patron saint of the church the bishop of Tournai founded here in 1217 - grew up in the part of Flanders called the Waasland, between the river Scheldt and the river Durme. By 1241 it was the administrative center of the region. In 1248 Margaret II added more territory to the parish on one strange condition: that the central area stay open and unbuilt. Whatever practical purpose she had in mind - markets, militia drills, a place to keep the herds at fair time - the consequence is the Grote Markt as it stands today, a horizonless cobbled plain ringed by the town hall, the Church of Saint Nicholas, and the gold-domed Onze-Lieve-Vrouwekerk. Stand at one corner of it on a quiet morning and the far side looks unreasonably distant for a place inside a city.

Sint-Niklaas does not shrink from the implication of having so much room. The city has at various points hosted the largest Christmas tree in Europe and, in 2005, the largest Easter egg - actual, recorded record-holders, the kind of stunt only a town with this much square footage can reasonably attempt. Three towering processional giants - Janneken, Mieke, and Sinterklaas with Zwarte Piet - parade across the same square at festival time, along with the three Magi: Caspar, Melchior, Balthasar. The Magi are an old tradition. The Easter egg was 8.3 meters tall. The town has earned the right to be slightly extra.

On the south side of the Grote Markt sits the Mercator Museum, dedicated to the cartographer Gerardus Mercator - whose projection still shapes how we draw the world on flat paper. The museum holds two original globes Mercator made in 1541 and 1551, one terrestrial and one celestial, both rare survivors of an era when a globe was both a scientific instrument and a piece of state-of-the-art furniture. Mercator was born in nearby Rupelmonde and worked in Leuven and Duisburg, but Sint-Niklaas keeps his archive. The cartographer who flattened the world has his roundest objects preserved a few kilometers from his birthplace.

The 20th century touched Sint-Niklaas hard at the start of the Second World War. The Luftwaffe bombed the city four times in May 1940, opening with light incendiary bombs on the road from Ghent to Antwerp and escalating. The worst attack came at 12:30 on the 17th of May. Bombs hit the Dalstraat, Gasmeterstraat, Molendreef, and Spoorweglaan, killing more than 80 civilians, including 51 refugees from the Dutch city of Breda who had taken shelter in a girls' elementary school on Gasmeterstraat. Seventy died instantly. A bomb hit the Church of Saint Nicholas on 19 May but failed to detonate; another raid the next day broke its leaded windows. By the end of May 1940 the textile industry that had carried the city for centuries - flax in the 16th century, cotton from 1764 onward - was wounded along with the streets, and after the war it never fully recovered. Today the city center is a shopping district. The school on Gasmeterstraat is remembered.

The Vredesfeesten - Peace Festival - opens the first weekend of September and turns the Grote Markt into a balloon field. Burners hiss. Envelopes inflate against the cobbles. Crowds press back to give the pilots room. The Villa Pace music festival runs three days alongside it. By Saturday night the square is a forest of striped envelopes and small flames in the dusk, and the largest market square in Belgium does the thing it has been quietly built for since 1248 - holding a crowd, with room left over. Margaret of Flanders, somewhere in a long memory, gets her practical use.