Sonderbuch (The municipality of Zwiefalten), The county of Reutlingen
The so-called Schlossberg was a motte-and-bailey castle and was probably built in the 11th century by the Lords of Sonderbuch. Before that, the hill could have been the site of a pre-Christian barrow. After the 13th century, there is no longer any proof of the castle being inhabited.
Today, it is located on a meadow, which is privately owned but freely accessible, and the only remains are a rampart and a moat.