 A keep from the destroyed 14th-century castle that had formerly stood on the site was included in the construction and is the oldest part of the castle.The prior castle had been burned down along with most of the town on 10 August 1552 by the troops of Albert Alcibiades, Margrave of Brandenburg-Kulmbach.Until the end of the ecclesial principalities in Germany in 1803, "Schloss Johannisburg"was the second residence of the Prince Bishop of Mainz, the first residence being the Electoral Palace in Mainz.