The Clementinum Astronomical Tower and Baroque Library

The route through part of the former Jesuit college will take you to the Baroque Library, the most beautiful of the Clementinum’s halls, the Meridian Hall with period astronomical instruments and the Astronomical Tower, the longest continuously-measuring meteorological station in the Czech lands. The Clementinum complex is the second largest building complex in Prague after the Prague Castle. →

After arriving in the city, the members of the Society of Jesus began to build their first Jesuit College in Prague in 1556. The construction of the entire complex, in which important Baroque builders such as Carlo Lurago, Francesco Caratti, Giovanni Domenico Orsi, Kilián Ignác Dientzenhofer, František Maxmilián Kaňka and others participated, took more than 170 years. After the abolition of the Jesuit Order in 1773, the premises were used for cultural and educational institutions. In 1928-1930, a substantial part of the premises was adapted for the needs of the National Library by architect Ladislav Machon.

The Baroque Library, one of the most beautiful Baroque libraries in the world, is located in the annexe of the Astronomical Tower above the Mirror Chapel. The library hall with large historically valuable globes is distinguished by the beautiful fresco decoration by Josef Hiebel. The upper part of the vault depicts the allegory of the sciences known by reason, while the lower part is dedicated to the revealed truth. The hall was completed in 1727, probably according to the plans of the important Baroque architect Kilian Ignaz Dientzenhofer. It is unique for its original form; it has not been damaged, altered or rebuilt in any way during its history. The books are stored in oak inlaid bookcases. On the ground floor there are mainly foreign-language theological works, and in the gallery there are general scientific writings. The library collection, which is still open, comprises over 27,000 volumes.

The Meridian Hall is located on the 2nd floor of the tower. Since the 18th century, this unique room has housed a unique slotted sundial. Through a small hole high in the wall, a ray of sunlight penetrated and turned the small space into a camera obscura. The image of the sun fell on a string stretched on the floor and their fusion determined with great precision the moment of local noon, the exact time when the sun is at its highest point in its orbit.
Two original astronomical instruments - mural quadrants - have also been preserved in the walls of the hall.

The Astronomical tower was completed in 1722, probably according to a design by F. M. Kaňka or K. I. Dientzenhofer, while it is likely that Anselmo Lurago collaborated on the modifications. The top of the 68-metre tower is adorned with a lead statue of Atlas carrying the celestial sphere on his shoulders.  Around 1750, the original observation tower was equipped with astronomical instruments and astronomical and meteorological measurements began to be taken here. The unbroken series of daily meteorological measurements started on 1 January 1775. From the gallery of the tower, for more than eighty years (1842-1928), noon was announced to the citizens of Prague. Now the tower offers visitors a magnificent view of the centre of Prague.

You can find more information here

Offer of services

Tours of the building

  • The guided tour includes a view into the Baroque Library, the Meridian Hall and the Astronomical Tower with a view from the gallery.
  • Tour duration approx. 50 minutes.

Rental of the building

  • Non-traditional tours of the tower outside opening hours
  • Private tours of the tower for corporate events or individuals
  • Bespoke tours for schools or special interest groups

Opening hours

  • January – March 26: Whole week 10:00 – 18:00
  • March 27 - September: Whole week 09:00 – 20:00
  • October – December: Whole week 09:00 – 19:00

Admission

Tickets must be purchased as eTickets. Tickets can be purchased for Czech and English tours. Tours are limited in capacity. We do not guarantee the possibility of purchasing tickets directly at the Klementinum box office.

basic | reduced | family:  CZK 380 | CZK 230 | CZK 810
Multi-ticket "9 objects in 365 days": CZK 990 | CZK 690 |  –  |
Early Bird Discount initiative: 50% off the admission fee every day during the first hour after opening
10% discount on admission when buying an eTicket online

Free admission for children under 5.  Persons with a ZTP/P card are admitted free of charge with 1 accompanying person.
The reduced admission fee is intended for children aged 6-15, students under 26, seniors over 65, and holders of disability identification card ZTP.
The family ticket is valid for 2 adults and up to 4 children.

Complete price list of admission

Contacts

Klementinum 190
 Praha 1 - Staré Město

General information

Rentals, events

Operations manager

The sightseeing route is not wheelchair accessible.