Contributions appreciated

"From the early 10th to the early 19th centuries it was the property of the archbishops of Mainz. They converted the old fortress into a residence in the 12th century. Originally, it was right on the bank of the Rhine, surrounded by water. Its more than two-meter-thick walls withstood all offensives... After being secularized in 1803, the castle had several owners until the town of Ruedesheim purchased it in 1941."

— Posting at World66, http://www.world66.com/europe/germany/hessen/rudesheim/sights