Saarbrücken Castle occupies a commanding position above the River Saar, its baroque facade designed by Friedrich Joachim Stengel in the 18th century for the princes of Nassau-Saarbrücken. The interior now houses the Historisches Museum Saar, which covers the history of the Saar region from prehistoric times through the industrial era to the post-war referendums on French or German sovereignty.
The museum is particularly strong on the complicated 20th-century history of the Saarland — a region that was administered separately from Germany after both world wars and only rejoined the Federal Republic after a referendum in 1955. The castle terrace has good views over the river and the old quarter below.