Tartu Cathedral (Estonian Tartu toomkirik) is one of the landmarks of the city of Tartu. The building is now an imposing ruin overlooking the lower town. In the small part of it that has been renovated is now located the museum of the University of Tartu, which the university also uses for major receptions.
The hill on which the cathedral later stood (Toomemägi or "cathedral hill") was one of the largest strongholds of the pagan Estonians, and the strategic nature of the site makes it likely that it had been since the earliest times. It was destroyed in 1224 by the Christian invaders of Livonia. Immediately after the conquest the Christians began construction of a bishop's fortress, the Castrum Tarbatae, on this strategic spot. (Parts of the old walls of the previous structures have since been revealed by archaeological excavations).
The construction of the Gothic cathedral on the north side of the cathedral hill was probably begun in the second half of the 13th century. It was surrounded by a graveyard and houses for the members of the cathedral chapter. The cathedral was dedicated to Saints Peter and Paul, who were also the patron saints of the city. It was the seat of the Bishopric of Dorpat, and one of the largest religious buildings of Eastern Europe.
The church was originally planned as a basilica, but the later addition of the three-aisled quire gave it the character of a hall church. The quire (in an early form) and nave were already in use by 1299. The cathedral was completed at the end of the 16th century with the building of the two massive fortress-like towers, originally 66 metres high, on either side of the west front. A wall separated the cathedral grounds and the bishop's fortified residence from the lower town.
In the mid-1520s the Reformation reached Tartu. On 10 January 1525 the cathedral was badly damaged by Protestant iconoclasts, after which it fell increasingly into decay. After the deportation to Russia of the last Roman Catholic Bishop of Dorpat, Hermann Wesel (bishop from 1554 to 1558; died 1563), the cathedral church was abandoned. During the Livonian War (1558–1583) Russian troops devastated the city. When in 1582 the city fell to the Poles, the new Roman Catholic rulers planned to rebuild the cathedral, but the plans were abandoned because of the ensuing Polish-Swedish War (1600–1611). A fire in 1624 compounded the damage.
In 1629 Tartu became Swedish, and the new rulers showed little interest in the derelict building, which during their time fell further into ruin and neglect, except that the burials of the townspeople continued in the graveyard well into the 18th century, while the main body of the church served as a barn. In the 1760s the two towers were reduced from 66 metres to 22 metres, the level of the nave roof, and made into a platform for cannon. The main portal was walled up at this time.
With the re-founding of the German-speaking University of Dorpat by Tsar Alexander I of Russia in 1802, the Baltic German architect Johann Wilhelm Krause was commissioned to build among the cathedral ruins the university library, a three-storey building erected between 1804 and 1807. At the end of the 19th century the northern tower was converted for use as a water tower.
In the 1960s the library building was extended and fitted with central heating. When it was replaced in 1981 by a new university library building, the old library became the home of the historical museum of the University of Tartu (Estonian: Tartu Ülikooli ajaloomuuseum). A thorough building conversion took place in 1985, when the 19th century interior was largely restored. Today the museum contains displays of important artefacts of the university's history, scientific instruments and rare books. The rest of the cathedral ruins and the external walls of the quire have been structurally secured and consolidated.
Reference: Wikipedia
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.