Trifels Castle was made famous because of its use in imprisoning many important people - most notably King Richard the Lionheart of England. Although in a ruinous state today, the castle was once quite splendid and fortified. It was built in the 11th century, and used extensively until the 13th century. Its decline followed over subsequent centuries, however much still remains, including the strong tower and other buildings. It was partially restored in the 1800s and 1900s, and is now open to the public to tour.