The Astronomical Tower was erected together with the completion of the Baroque library and of the Mirror Chapel, all of this undertaken under the direction of the university´s chancellor Frantisek Retz. The tower is crowned with a statue of an Atlant holding the celestial sphere on his shoulders.  Originally the tower served only as an outlook spot but Josef Stepling, a study director at the Philosophical Faculty, equipped the tower with astronomical instruments and thus transformed it into an astronomical observatory for both scientists and students. The computation and designs necessary to construct these instruments were provided by a Professor of mechanics, a Jesuit, Jan Klein.

The instruments he produced were among the best of what his epoch could offer. Jesuit astronomers determined the Prague meridian and, from their tower, they signalled every noon. This signal was followed by a cannon shot to mark the middle of the day for the whole of Prague. This tradition was observed till the times of the First Republic in the first half of the twentieth century. The tower was used for astronomical observation till the 1930s.

CLEMENTINUM - entrance:
Křižovnická 190
Karlova 1
Mariánské nám. 5
Praha 1

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+420 222 220 879

Design: RNDr. Filip Pešek, PhD