Piedrabuena Castle is part of defense line of Guadina and Tajo rivers near Portugal border. The oldest parts date from the late 14th and early 15th centuries. It has been head of the Encomienda of the Order of Alcántara since the 13th century.
The exterior enclosure is a quadrangular construction with cylindrical towers at the corners. In the interior there are four corridors, the keep and the prison tower. The residential function of this building is easy to see, with galleries open to the outside and a cloistered patio, all in the manner of an urban palace.
Today Piedrabuena Castle is privately owned.
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.