We visited Schloss Lichtenstein in early September. The weather was gorgeous and the castle was stunning. It is small but definitely a sight to see as it sits high atop a hill overlooking a beautiful valley. We paid a small admission fee of 2 euros for each adult to walk the castle grounds freely. You definitely need a car to get here but the view is amazing and worth the quick stop.
If you are would like more information about the castle such as its history or prices for tours you can click on the link above. It will take you directly to the official website that is in German and English.