Overlooking one side of Schlossplatz is massive Altes Schloss or Old Castle. There is no trace of its 10th-century origins; the existing building with its beautiful courtyard surrounded with multiple arcades was built between 1553-78.
The impressive structure now houses the Württemberg Landesmuseum, with its fascinating collections of medieval art, musical instruments, watches, and clocks, as well as the magnificent Württemberg royal crown and crown jewels.
Especially interesting are the archaeological collections, with rare artifacts tracing prehistoric inhabitants of the caves in the Swabian mountains, including the world's oldest human artworks.
