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World's oldest clock? Not even close.

Known locally as the Prague Orloj, this clock was for many years believed to have been built in 1490. But subsequent investigations later show that whilst the calendar and the gothic sculptures probably date from that period, parts in the centre date back to 1410. It is still a relative newcomer compared to the others in this series but it qualifies for inclusion because of its appeal and interest.

The Old Town Hall clock is one of the most famous and one of the most visited astronomical clocks in all of Europe. Over the centuries it has been repaired, modified and extended many times. The original construction is attributed to Jan Sindel, who was professor of mathematics and astronomy at Charles University in Prague, and Mikulas of Kadan, a local clockmaker.

Jan Taborsky, a clockmaker, looked after the clock in the mid 16C and a repair by him is recorded in 1552. Many more repairs followed and the moving statues were added during the following century.

A full overhaul was carried out in 1866, when the twelve Apostles were also added. But large parts of the clock needed to be restored again after German soldiers used incendiaries to destroy it during the Prague uprising towards the end of the second World War. The restoration took three years.

More recently, it was overhauled and cleaned again in 1979, the residents taking great pride in it. A great many tourists gather each hour to watch the activity, made all the more enjoyable by the clock sitting low in the tower rather than at the very top.

It is an immensely complex clock but there are three main parts to look out for. At the very top (just above the main dial) the Apostles present themselves at the doorways on the hour, all twelve appearing at midday. Four animated figures also spring into life each hour, including a skeleton, representing Death, which strikes the bell. At the bottom is the calendar dial showing the day, the Saint for that day, the months and the seasons.

Then between the two is the main dial, which is the oldest part of the clock and the most complex. Note that the centre is static, the outer chapter ring rotates in both directions, and the inner zodiacal ring rotates off-centre. There are three hands, or pointers, which show a great many things from Central European Time, Temporal Time (the ancient system which involved dividing daylight hours into twelve, so in different seasons, hours had different lengths), Bohemian Time (similar to Temporal but dividing daytime into 24 hours), the sun's position in the Zodiac, Sidereal Time for astronomers to track a particular star (which will be in the same position at the same sidereal time each day), and the moon phase.

If you still want to know more, check out this very informative website devoted to the clock, where you can even download their Excel spreadsheet for a better understanding.

On 9 October 2010, the town celebrated the clock's 600th anniversary, and now that you've read some of the construction, destruction, reconstruction, modernisation and aging through history that it underwent, you really must see the celebratory ten-minute spectacular - watch it with the sound on, right through to the orbital launch at the end. The initial noise of the gathered crowd quickly disappears as they stand in awe, and then in silence as their jaws drop! You'll want to watch it again and again, I promise you.

Click here to read more about the next clock in this series of articles, the DOVER CASTLE clock.


  • Old Town, Prague
  • Celebration movie of the Orloj, Praha
  • Prague's orloj, lower dial
  • Prague's Old Town Square at night
  • Prague clock movement