The construction of the Niebla Castle started in 1402, when Don Enrique de Guzmán, the second Duke of Medinasidonia and the fourth of Niebla, pulled down the old Moorish Alcázar to build the one we know today. The result was a magnificent royal palace which preserved the most interesting and luxurious parts built by the Arabs, such as the Muslim Tower of Homage.
After the works of restoration made in the last few years, the Alcázar is now in good conditions. It has a rectangular structure divided by an inner wall which separates the patio of arms from the luxurious rooms intended as palace. This main structure has ten towers; six of them are square (four are on the corners -including the Tower of Homage - and two of them are at the ends of the inner wall). The other four are semicircular cubes alternated with the square ones. The walls go on from the Tower of Homage and the one located on the north-west angle to form a barbican surrounding the central building on the east, south and west sides. This barbican has six towers and joins the almohade wall near the Puerta de Sevilla and del Socorro. An adarve and a barbican built in the late 15th century completed the building.
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.