Built by Lord Konrad II Reiz von Breuberg around 1250, this hulking, partly ruined hilltop castle was visited by Mary Shelley on her German travels in 1814, inspiring the title of her famous novel and its protagonist. Tours are in German but you're free to walk around the castle and grounds. It's home to a panoramic restaurant and hosts events, including one of Europe's largest Halloween parties. From Darmstadt, it's 13km south, high up in the forest, via the B426.
Other events here include medieval banquets, costumed adventure castle days, live music including jazz, magic shows, and theatre nights for adults and children – schedules are posted online.