Count Otto II of Guelders granted Harderwijk city rights in 1231, and the wall went up over the rest of that century. By around 1252 the town had attached itself to the Hanseatic League, the loose merchant federation that ran northern European trade from Bruges to Novgorod. Harderwijk's geography was unimpressive — a sandy rise on the Veluwe's western edge, opening onto shallow water — but the shallowness was the point. Boats unloaded onto a wooden pier outside the Vischpoort, and bigger ships anchored offshore and shuttled cargo in by lighter. The town held the staple right on fish landed between Muiden and Kampen, meaning any catch in that stretch of coast had to be brought through Harderwijk's gates and sold at Harderwijk's price. About one in seven townspeople worked the fisheries. The fleet ran to 160 boats.

Between 1648 and 1811 the Gelderse Academy operated here — fifth in the Dutch Republic after Leiden, Franeker, Groningen and Utrecht, and the smallest by some distance, with a cap of roughly 150 students at a time. Its reputation, then and now, rests on speed. Harderwijk would award a medical doctorate for a fraction of what Leiden charged and in a fraction of the time. In the spring of 1735 a twenty-eight-year-old Swede named Carl Linnaeus arrived with a thesis already written, sat his exams, and walked out a doctor of medicine within two weeks — about one of which was spent waiting for the printer. He went on to invent the system that names every species on Earth. A small spire in the old town, the Linnaeustorentje, marks where the university stood. Napoleon closed the school in 1811.

For most of Harderwijk's history the Zuiderzee defined everything: the trade, the food, the smell, the calendar. The Afsluitdijk changed all of that in a single summer. Once the saltwater was sealed off from the North Sea it began to freshen, and the herring, anchovies and shrimp that had supported the fleet died out. Only eels, pike and a few hardy freshwater species survived. Harderwijk's harbor today holds yachts where it once held smacks. Aaltjesdag — Eel Day — is celebrated each summer to honor what was lost, with smoked eel from the boulevard stands. You can still buy fish there most of the year, but no one in town makes a living from it anymore. The IJsselmeer outside the Vischpoort is freshwater now. The lighthouse keeper's room sits empty above the gate.

Walk the western edge and the medieval fortifications surface in pieces — a stretch of curtain wall here, a stump of bastion there, a cannon pointed at nothing in particular near the Sint Catharinakerk. Of the five city gates that once controlled access to Harderwijk, only the Vischpoort still stands, crowned with the lantern that doubled as a Zuiderzee lighthouse from 1851 to 1947. The oldest streets — Hoogstraat and Grote Poortstraat — sit on the original 13th-century footprint. The Grote Kerk dates from the 1315 southward expansion of the town, the second wave of building that pushed Harderwijk past its first walls. Almost everywhere you walk in the old center, you are tracing the outline of a Hanseatic merchant port that has been quietly outliving its own purpose for nearly a hundred years.

About 50,000 people live here now. The Dolfinarium — Europe's largest marine mammal park — draws the day-trippers, though its long-running controversies have made the town as much a debate as a destination. The Veluwe begins on the eastern edge of the municipality, all heath and pine forest and red deer, and most visitors who stay overnight come for that as much as for the harbor. Harderwijk still calls itself a Hanzestad, and on summer weekends the old town fills with people drinking coffee on the Vischmarkt where fish auctions used to run before dawn. The sea that made the town is gone. The town the sea made is still standing, and that turns out to be the more interesting story.