Where is Fort-Mardyck?

Grande-Synthe1.6 km · 1.0 mi → Saint-Pol-sur-Mer2.3 km · 1.4 mi → Cappelle-la-Grande4.8 km · 3.0 mi → Dunkerque4.9 km · 3.0 mi → Coudekerque-Branche6.1 km · 3.8 mi → Armbouts-Cappel6.6 km · 4.1 mi → Spycker6.7 km · 4.2 mi → Loon-Plage7.2 km · 4.5 mi → Coudekerque-Village8.3 km · 5.2 mi → Brouckerque8.3 km · 5.2 mi → Steene9.5 km · 5.9 mi → Téteghem9.7 km · 6.0 mi →

Abscon50.33333, 3.30000 → Allennes-les-Marais50.53754, 2.95361 → Anhiers50.40737, 3.15512 → Aniche50.32995, 3.25346 → Annoeullin50.52925, 2.93180 → Anor49.98999, 4.10049 →