The Tower of Motta Sant'Anastasia was built between 1070 and 1074 by the will of the Count Roger of Hauteville. The massive tower with a rectangular plan, with a base of about 21.5 by 9 by 17 metres, is about 21 metres high and is a typical defensive structure of the early Middle Ages. The roof terrace retains almost intact battlements.
The structure consists of three elevations. Only the first of these is still the original arched windows ogive (external) and at all sixth (inside). The other two square windows, on other levels, such as the current front door, go back to the 15th century.
The ground floor was designed for military housing. In it there are a number of holes for defence.
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.