Rothenthurn ('red tower') castle may have existed since the 11th century. It was an estate of the Counts of Ortenburg and their successors, the Counts of Celje. A castle is documented in 1478, when the area was held by the Meinhardiner House of Gorizia. The present-day Renaissance building with its chapel was erected from the early 16th onwards, it was acquired by Christoph Khevenhüller about 1525 and afterwards in the possession of several local nobles over the centuries. Today the owners run the castle as a lodging establishment.
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.