The Prague astronomical clock was first installed in 1410, making it the third-oldest astronomical clock in the world and the oldest one still operating. It is mounted on the southern wall of Old Town Hall in the Old Town Square. The clock mechanism itself is composed of three main components: the astronomical dial, representing the position of the Sun and Moon in the sky and displaying various astronomical details; 'The Walk of the Apostles', a clockwork hourly show of figures of the Apostles and other moving sculptures—notably a figure of Death (represented by a skeleton) striking the time; and a calendar dial with medallions representing the months. According to local legend, the city will suffer if the clock is neglected and its good operation is placed in jeopardy and a ghost, mounted on the clock, was supposed to nod his head in confirmation. Based on the legend, the only hope was represented by a boy born in the New Year's night.
The oldest part of the Orloj, the mechanical clock and astronomical dial, dates back to 1410 when it was made by clockmaker Mikuláš of Kadaň and Jan Šindel, the latter a professor of mathematics and astronomy at Charles University. Later, presumably around 1490, the calendar dial was added and clock facade was decorated with gothic sculptures.
The clock stopped working many times in the centuries after 1552, and was repaired many times. In 1629 or 1659 wooden statues were added, and figures of the Apostles were added after major repair in 1787–1791. During the next major repair in years 1865–1866 the golden figure of a crowing rooster was added.
The clock suffered heavy damage on May 7 and especially May 8, 1945, during the Prague Uprising, when Germans set fire from several armoured vehicles and an anti-aircraft gun to the south-west side of the Old Town Square in an effort to silence the provocative broadcasting initiated by the National Committee on May 5. The hall and nearby buildings burned along with the wooden sculptures on the clock and the calendar dial face made by Josef Mánes. After significant effort, the machinery was repaired, the wooden Apostles restored by Vojtěch Sucharda, and the clock started working again in 1948.
The clock was last renovated in autumn 2005, when the statues and the lower calendar ring were restored.
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.