Schloss Hollenburg is a medieval castle near Köttmannsdorf. It is on a rock of the northern slope of the Drava valley. One Swiker, Lord of Hollenburg in the Duchy of Carinthia was first documented as a witness in the 1142 deed of the foundation of Viktring Abbey. He may have been a liensman of the ducal House of Sponheim; his son Reginher is mentioned as Lord of Steuerberg, he accompanied King Conrad III of Germany on the Second Crusade in 1147 and later appeared as a ministerialis of Margarve Ottokar IV of Styria.
The castle was of strategical importance due to its location at a Drava river crossing and the road to the Loibl Pass and the March of Carniola. Upon the extinction of the Hollenburg dynasty in 1246, it passed to the Styrian Lords of Pettau, in 1438 it was inherited by the House of Stubenberg. The structure had been severely damaged by the 1348 Friuli earthquake.
In 1514 the Habsburg emperor Maximilian I, stuck in the War of the League of Cambrai against Venice and highly indebted, sold Hollenburg to Lord Siegmund of Dietrichstein, elevating him to the rank of a Freiherr (Baron). The House of Dietrichstein had the castle rebuilt in a Renaissance style, finished in 1588. The Dietrichsteins held the castle until the extinction of the branch in 1861, it was acquired by the Wittgenstein family in 1913.
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.