Ehrenfels Castle was probably built in the first half of the 13th century. The first mention of the Lord of Ehrenfels is in 1257. In 1320 it was owned by Burkhard and Rudolf von Schauenstein, who also used the name Ehrenfels or Herrenfels. They probably expanded the simple bergfried with residential space and a ring wall around that time. The castle was first mentioned in 1423 with Hermann von Ehrenfels as the owner. Toward the end of the 15th century or in the early 16th century it was given to Cazis Monastery, but the Schauenstein-Ehrenfels family continued to occupy it. During the 16th century the castle was renovated and rebuilt into a more comfortable palas.
However, by 1600 Ehrenfels was abandoned and began falling into ruin. Parts of the castle were demolished for building material, and when the Ehrenfels-Schauenstein male line died out in 1742, only a ruin remained. In 1933 it was acquired by the Schweizerische Burgenverein (Swiss Castle Association) and converted into a youth hostel. Since the conversion was done without archeological investigation or records, much of the history of the castle was lost. In 1954 Swiss Youth Hostels bought the castle from the Association. It remains in operation today with 38 beds.
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.