The fortress was built by the Dutch in the 19C, on the site of the former prince-bishops' castle (demolished in 1717). Resistance members and hostages were held here from 1940 to 1944. Visitors can now see a Resistance and concentration camp museum, and the former dungeons and interrogation rooms. From the glacis, there are splendid views of the old town, River Meuse and surrounding area. The nuclear power station at Tihange (1975) can be seen to the northeast.