Tretower Castle is a Grade I-listed ruined castle in the village of Tretower. It was founded as a motte and bailey castle by Picard, a follower of Bernard de Neufmarché. Probably around 1150, Picard's son, Roger Picard I, replaced the motte with a shell keep. By about 1230 a tall cylindrical keep was added to the inside of the shell keep, possibly by his great-grandson, Roger Picard II, and the space between was roofed over. At this time the earlier bailey was walled in stone and provided with cylindrical corner towers. In the early 14th century residential buildings were constructed away from the original fortifications forming today's Tretower Court. Over time the lords of Tretower favoured the more luxurious Court and the castle fell into disuse.
The castle is roughly triangular in plan, with the motte and keep assemblage occupying the western corner. The 12th century shell-keep is an irregular enclosure with a gate-tower on the line of approach from the bailey. In the centre of the shell stands the tall cylindrical 13th century keep. The keep is of three storeys, with an original entrance at first floor level, above a strong, slanted batter or talus. The top of the talus is marked by a decorative string-course of stone.
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.