Plassenburg Plassenburg is a castle in the city of Kulmbach in Bavaria . It is one of the most impressive castles in Germany and a symbol of the city . It was first mentioned in 1135 . The Plassenberg family were ministerial of the counts of Andechs ( later the dukes of Andechs - Meranien ) and used as their seat the Plassenburg . The House of Guttenberg , a prominent Franconian noble family , traces its origins back to 1149 with a Gundeloh v . Blassenberg ( Plassenberg ) . The name Guttenberg is derived from Guttenberg and was adopted by a Heinrich von Blassenberg around 1310 . From 1340 , the Hohenzollern s governed from Plassenburg castle their territories in Franconia till 1604 . The Plassenburg was fortress and residence for the Hohenzollerns . It was destroyed in 1554 at the end of the second Margravian war ( 1552 – 1554 ) of margrave Albert Alcibiades . The Plassenburg was later rebuilt by the architect Caspar Vischer as an impressive stronghold and as a huge palace . In 1792 , Margrave Alexander sold the Plassenburg to his cousin , the King of Prussia . A combined Bavarian and French army under the command of Jérôme Bonaparte , brother of Napoleon , besieged the Plassenburg in 1806 . In 1810 , Kulmbach became Bavarian and the castle was used as a prison and as a military hospital . During the second world war , the Organisation Todt used the Plassenburg as a training camp and recreation home . Today , it is a museum and a venue for cultural events . It contains a significant collection of Prussian military artifacts and portraits . History . The Plassenburg was first mentioned in 1135 , when it was described by Count Berthold II of Andechs as " comes de Plassenberch " . Presumably he was also the founder of the castle , which was built to the west of an earlier fortified farmstead . To begin with , the castle was a central supporting stronghold for the Meranian rulers of the Upper Main and Franconian Forest . After the death of the last Andechs - Meranian , Duke Otto VIII , his brother - in - law divided his inheritance . The Plassenburg with Kulmbach , Berneck , Goldkronach , Wirsberg , Trebgast and Pretzendorf ( now Himmelkron ) went to Hermann III and Otto III , the Counts of Weimar - Orlamünde . The two sons of Herman II ( died 1247 ) and Beatrix of Andechs - Merania initially ruled together as " Lords of Plassenburg " . After 1278 they divided the inheritance of their father , whereupon Otto III was given sole possession of the domain of Plassenburg and the territory around Weimar . Otto III died in 1285 and the Plassenburg appeared soon afterwards in the hands of his son Otto IV . His son in turn , Count Otto VI of Orlamünde , who was the only Orlamünde since 1323 who was described as " Lord of Plassenburg " , pledged this lordship together with the Plassenburg , Kulmbach , Trebgast and Berneck in 1338 to Burgrave John II of Nuremberg . As a result , after Otto VI ' s death in 1340 , Plassenburg fell to the burgraves of Nuremberg from the House of Hohenzollern . Gradually , the Plassenburg developed into a new centre of power for the Hohenzollerns . At the time of Burgrave Frederick V of Nuremberg ( who reigned 1357 – 1397 ) , the Plassenburg had already outstripped the Cadolzburg - a traditional burgravial residence . In 1397 Burgrave Frederick V stepped down from the business of government and chose the Plassenburg as his retirement home . The Hohenzollerns ' territory in Franconia was divided between his sons , John III and Frederick VI , later to be the Elector of Brandenburg , in accordance with the " Dispositio Fridericiana " of 1385 . Thus the Plassenburg became the centre of power for the so - called Principality of the Mountains ( " Fürstentum ob dem Gebirg " ) , later the Margraviate of Brandenburg - Kulmbach . After the death of John III in 1420 , his estate fell to his brother , Frederick , who , in 1421 , created the office of " Captain of the Mountains " to rule his domain . Plassenburg remained the administrative centre of this hilly principality until after the middle of the 16th century . The internment of the Countess Barbara of Brandenburg in March 1493 , began the sad chapter of Plassenburg as a family prison . This reached a peak in February 1515 when Margrave Casimir of Brandenburg locked up his father , Margrave Frederick the Elder of Brandenburg , in a tower room at Plassenburg which he could not leave for 12 years . In 1542 Margrave Albrecht Alcibiades moved the " Residenz " for the first time from Plassenburg , which continued to serve primarily as a country fortress , to Bayreuth . References . German language Wikipedia : . Retrieved October 18 , 2005 .