De Gesloten Steen in Utrecht

You're standing at the corner of the Oudegracht and the Eligenhof, right in the centre of Utrecht. Look down at the corner of the building. There's a big, heavy boulder sitting there, and it's chained up. This is De Gesloten Steen, the Locked Stone, also known as the devil's stone. It's a listed national monument, and the corner house behind it is named after it.