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Astronomical clock on the Old Town Square

At the top of the hour, people can be seen rushing to the Old Town Hall, and suddenly all of them stand still and stare at a wall. The Prague Town Hall Clock is located on the south wall of the Old Town Hall. It is also known as the Apostle Clock or Old Town Astronomical Clock.

Astronomical clock

In 1338, the citizens of Prague received permission from King John of Bohemia to build a town hall. The tower was almost 70 meters high and was only finished in 1364. On this tower, a clock was installed, but it wasn’t manufactured as a whole, it was developed piece by piece over many years.

The clock face with its astronomical design is regarded as the oldest part of the clock today. It was built in 1410 by the clocksmith Mikuláš z Kadaně. The masonry work and sculptures were made separately.
In 1490, a calendar was added below the face. In addition, new sculptures were prominently attached to the clock’s facade.
Jan Táborský z Klokotské Hory was commissioned with the maintenance and restoration of the town hall clock in 1551. He installed a new drive for the calendar and introduced the half hour indicator and two sundials. In the 17th century, the clock was extended with additional figures next to the clock faces.
The 12 Apostles were installed in the windows above the astronomical clock face, but the exact moment in time when this happened cannot be determined. The weathercock was evidently installed in 1882.
Since 1954, the clock can be electrically wound up. The manual procedure is no longer necessary.

Over the course of time, the clock was repaired several times, pieces were replaced or modernized until the clock finally developed into the appearance which it is known for today.


Astronomical clock on the Old Town Square

The clock shows, among other things:

  • Old Bohemian Time (the gothic numerals)
  • Central European Time (the Roman numerals)
  • Babylonian Time (the Arabic numerals)
  • Sidereal Time (the zodiac in the middle)
  • Movement of the heavenly bodies

The mechanics of the Astronomical Clock are very complex. For us, it was not necessary to understand the mechanics behind the clock to appreciate its fascinating appearance. It was just interesting to get to know a different kind of clock, to discover the characters and design elements and to experience the enthusiasm of the spectators. When the clock "wakes up" at the hour (between 9 am and 9 pm) the apostles appear in the windows next to the astronomical clock face, the hourglass turns over, the weathercock crows and the clock chimes the hour.

Astronomical clock on the Old Town Square

If you would like to get more detailed information, you can find useful information on this page.

The Astronomical Clock can also be seen in some films. Those familiar with the Harry Potter movies will certainly recognise it.


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