The Roman aqueduct of Segovia was built, probably in the 1st century BC, to bring water from the mountains to the hilltop settlement of Segovia. It was a massive feat of engineering as it ran for around 15 km and had to cross a wide valley before it entered the city. It was used to bring water to the town until the 19th century.
Today the aquduct is part of a UNESCO World Heritage Site that also includes the old city and fortifications of Segovia. It is an enormous construction of masonry, 813 m in length, consisting of four straight segments and two superimposed arcades borne by 128 pillars. At the lowest point of the valley, the Aqueduct stands at a height of 28.5 m above ground. The tall arches of the aqueduct bridge are a major tourist attraction.
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.