Hohenasperg is a flat-topped sandstone hill about six kilometres west of Ludwigsburg, fortified continuously from Celtic times through the Middle Ages and converted into a state prison under the Württemberg dukes in the 17th and 18th centuries. The fortifications still ring the summit, enclosing a remarkable little town within the walls. The hill is sometimes called the Demokratenbuckel — the Democrats' Hump — for the long list of political prisoners held here.
Today most of the buildings are used by the local administration and as a regional prison, but the museum near the entrance covers the site's history and the bastions can be walked freely. The view across the Neckar valley is excellent, and on clear days you can see the Swabian Jura to the south. A pleasant walk down to Asperg town for lunch and back makes a half-day outing from Ludwigsburg. Reachable by S-Bahn (Asperg station) in 15 minutes.