Count Wilhelm II of Katzenelnbogen built the Katz Castle in the second half of the 14th century. Katz Castle was used as bastion and military base to protect the Rheinfels Castle. Together they formed a fortified bulwark with a barrier for levying of the Rhine toll. The extended view up to the bend of the river at the Loreley was also of great importance to secure salmon fishing. Due to the intentionally chosen location on the mountain ridge Katz Castle could not possibly be conquered from the valley.
Only after the invention of fire arms, Katz Castle had to be substantially reinforced. It was also upgraded as bastion against Maus Castle in the Electorate of Trier. At the same time the donjon of Katz Castle was raised to to ensure eye contact with Reichenstein Castle. In 1479 the family line of the Counts of Katzenelnbogen died out.
In succession of long-lasting disputes on heritage, Katz Castle and Rheinfels Castle were besieged, demolished, rebuilt and extended several times. Even though repairs had been made in 1800, Napoleon blew up Katz Castle in 1806.
In 1896 District Administrator Berg acquired Katz Castle, to reconstruct it as close as possible to the original design. From 1946 till 1951 Katz Castle served as local High School 'Institut Hofmann' including board
Since 1989 Katz Castle is private property of a Japanese and accommodates the hotel Katz Castle.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.