Llantilio Crossenny was a manor of the Bishops of Llandaff in the Middle Ages, and the site of their manor house can still be seen at Hen Gwrt. Their episcopal presence and the proximity of White Castle account for the 'exceptional scale' of the church. It is of Old Red Sandstone with a shingled spire. The tower and the nave are of the thirteenth century whilst the chancel was rebuilt in the fourteenth. The spire was added in the early eighteenth century and the whole was restored by John Prichard and John Pollard Seddon in 1856–7.
Either side of the East window of the chapel are two stone corbels which are said to represent Edward II. The interior also has a number of seventeenth and eighteenth century funerary monuments of high quality and stained glass by Charles Eamer Kempe.
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.