Skenfrith Castle was established by the Normans in the wake of the invasion of England in 1066, to protect the route from Wales to Hereford. Possibly commissioned by William fitz Osbern, the Earl of Hereford, the castle comprised earthworks with timber defences. In 1135, a major Welsh revolt took place and in response King Stephen brought together Skenfrith Castle and its sister fortifications of Grosmont and White Castle to form a lordship known as the 'Three Castles', which continued to play a role in defending the region from Welsh attack for several centuries.
At the end of the 12th century, Skenfrith was rebuilt in stone. In 1201, King John gave the castle to a powerful royal official, Hubert de Burgh. During the course of the next few decades, it passed back and forth between several owners, including Hubert, the rival de Braose family, and the Crown. Hubert levelled the old castle and built a new rectangular fortification with round towers and a circular keep. In 1267 it was granted to Edmund, the Earl of Lancaster, and remained in the hands of the earldom, and later duchy, of Lancaster until 1825.
Edward I's conquest of Wales in 1282 removed much of Skenfrith Castle's military utility, and by the 16th century it had fallen into disuse and ruin. The castle was placed into the care of the state by the National Trust in 1936, and is now managed by the Cadw heritage agency.
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.