The castle Kaltenstein is the landmark of Vaihingen an der Enz. Although the over 900 years old castle is currently empty and a new tenant is sought, you can enjoy the view of the city and the vineyards from the old defensive wall.
You cannot visit the inside of the castle. The Christian Youth Village used to be located here, then it stood empty for a long time and now an investor is to convert it into a hotel. However, you can walk around it (four steps!).