Het Steen (The Stone) is an ancient medieval castle built in the old city center of Antwerp, Belgium, which is one of Europe's biggest ports. Built around 1225 it is Antwerp's oldest building.
The castle was constructed in part to control access to the Schelde, the river that flows through this area. It was also used as a prison between 1303 and 1827.
There are often reports of weird noises and ghostly activity on the grounds of Het Steen.