Prague Orloj is the third oldest operating astronomical clock in the world.
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 decorated with gothic sculptures. In 1552 it was repaired by Jan Táborský, clock-master of Orloj, who also wrote a report on the clock where he mentioned Hanuš as maker of the clock. The Orloj stopped working many times in the centuries after 1552, and was repaired many times. In the 17th century moving statues were added, and figures of the Apostles were added after major repair in 1865-1866.
The Orloj suffered heavy damage on May 7 and especially May 8, 1945, during the Prague Uprising, when Germans directed incendiary fire from several armored 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 Orloj and the calendar dial face made by Josef Mánes.
The machinery was repaired, the wooden Apostles restored by Vojtěch Sucharda, and the Orloj started working again in 1948, but only after significant effort.
The Orloj undergone latest major renovations in 1994 and 2005.