Jordan's Castle's early history is somewhat obscure. The earliest authentic reference is to a defence of the castle by Simon Jordan against the O'Neills for three years, until relieved by Lord Deputy Mountjoy in 1601. In 1911 the Belfast antiquarian, Francis Joseph Bigger, bought the castle and restored it, using it to display his extensive collection of antiquities and making it freely accessible to everyone. When he died in 1926, the castle was presented by his executor, Dr Joseph Bigger, to the state on condition that, with its contents, it should be preserved as an Ancient Monument. The contents have since been dispersed among the Ulster Museums general collections and the tower is no longer open to the public.
Jordan's Castle is a rectangular tower house four storeys high. On the north face are two rectangular projections, one containing a stone spiral staircase, the other an inner closet at each level, with those on the lower stages having outlets to the ground. Architecturally there is little evidence to give a definitive date for the castle. The masonry is blue stone rubble with a little freestone in quoins and window jambs. Some of the window details suggest 15th century, but have had so much reconstruction that dating is difficult.
The ground floor chamber is unfloored and the irregular surface of the outcropping rock can be seen. It therefore may have been a storehouse. The main room is apparently on the first floor, which contains its original stone floor supported on a pointed barrel vault. The floors on the second and third storeys are at the original levels but of modern construction, with the beams going at right angles to the original direction. The concrete roof is also an addition. The wall tops retain their stone-flagged rampart walls and archery turrets. The turret to the north-west contains a dovecote, the nest-holes of which are contemporary with the main structure.
The entrance is at the bottom of the north-west tower and leads to a spiral stairway to roof level. It is protected by a machicolation at that level. The projecting towers are connected by a high-level arch which also functions as a machicolation.
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.