Prague Astronomical Clock

The Prague Orloj is a medieval astronomical clock set into the south wall of the Old Town Hall on Old Town Square, and it has been telling time, and a good deal more, since 1410. Its oldest parts, the clockwork and the astronomical dial, were made by the clockmaker Mikuláš of Kadaň with Jan Šindel, a professor of mathematics and astronomy at Charles University; the first written mention dates from 9 October 1410. Around 1490 a calendar dial was added below and the façade was dressed with Gothic sculpture. For centuries the clock was wrongly credited to a later master, Hanuš, and a legend retold by the writer Alois Jirásek holds that the city councillors had him blinded so he could never build another.

The astronomical dial is essentially a mechanical astrolabe, a model of the sky as seen from Prague. A blue disc stands for the sky above the horizon and the dark bands below for night, with dawn and twilight marked in between. A golden sun travels around a zodiac ring and shows the time three ways at once: ordinary hours in Roman numerals, the unequal "hours" of daylight on curved golden lines, and Old Czech Time on the outer ring, where the count restarts at sunset. The moon moves around the same ring faster and shows its phase through a half-silvered sphere turned slowly by a weight, a gravity-driven mechanism that is unique among clocks of this kind.

Most people come for the performance on the hour. The skeleton of Death, standing beside the dial, rings a bell, and the figures alongside, Vanity with a mirror, the Miser with his moneybag, and a Turk representing earthly pleasures, shake their heads as if refusing to go. Above the dial two small windows open and the twelve Apostles file past in turn; a golden rooster, added in the 1860s, completes the scene. The wooden Apostles themselves date from after a repair in 1787–91.

The clock has been close to lost more than once. On 8 May 1945, during the Prague uprising, German armoured vehicles shelled this side of the square; the town hall burned, along with the wooden figures and the calendar painted by Josef Mánes. It ran again in 1948, with new Apostles carved by Vojtěch Sucharda. A restoration from January to September 2018 replaced the electric drive installed in 1948 with an original mechanism from the 1860s, though the new copy of the Mánes calendar sparked a row in 2022 when critics complained that its figures had drifted far from the original. Across the square rise the 80 m towers of the Church of Our Lady before Týn and the Jan Hus Memorial of 1915.

Getting there

The clock is in the centre of Prague's Old Town, on Old Town Square. Václav Havel Airport Prague (PRG) is about 12 km away. The square is pedestrian and the clock can be watched from it at any hour.