Xanten Cathedral (Xantener Dom) is considered the biggest cathedral between Cologne and the North sea. The cathedral owes its name to Victor of Xanten, a member of the Theban Legion who was supposedly executed in the 4th century in the amphitheater of Castra Vetera for refusing to sacrifice to the Roman gods. This Roman camp is near today's town of Birten. According to legend, Helena of Constantinople recovered the bones of Victor and his legion and erected a chapel in their honour. During a modern excavation the existence of a 4th-century cella memoriae was discovered; however, it was determined that it had not been erected for Victor but for two other male corpses that were placed in the crypt at a later date.
The cornerstone of the cathedral was laid in 1263 by Friedrich and Konrad von Hochstaden. Construction lasted 281 years and was finally finished with the dedication of the Holy Spirit Chapel in 1544. The cathedral contains a five-aisle nave built in the Gothic style. In contrast to many other cathedrals of the period, St. Victor's lacks an ambulatory. Instead a twin pair of chapels is connected to the choir similar to that seen at the Church of Our Lady in Trier. Along with the monasterial library of the Cathedral houses one of the most important religious libraries of the Lower Rhine.
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.