Shengen in Luxembourg is best known as the location of the eponymous EU agreement permitting open borders between participating countries. The small town lies on the River Moselle at the boundaries of Luxembourg, France and Germany and the agreement was actually signed on a boat on the river at the precise junction between the three nations.
The town is less well known for ts former gypsum mines, which lie in a now-wooded area above the river. A trail leads from the town through the former workings with interpretive signage and plans along the way. The mines themselves have suffered several colapses and are no longer accessible.