Jens Olsen's World Clock, Mechanical astronomical clock in Copenhagen City Hall, Denmark.
Jens Olsen's World Clock is a mechanical astronomical clock housed in Copenhagen City Hall with over 15,000 individual parts. It displays global times, dates, planetary positions, and precise astronomical calculations all at once.
Watchmaker Jens Olsen designed this mechanical marvel as a personal passion and spent twelve years bringing it to completion. King Frederik IX and Olsen's granddaughter Birgit officially activated the masterpiece in 1955.
The clock reflects the importance of communal participation in Danish culture, with brass parts contributed by households across the country. This shared effort shows how ordinary people helped bring an extraordinary project to life.
The City Hall is open to visitors during specific weekday and Saturday hours so you can see the clock up close. It is best to check the exact opening times beforehand since hours can vary seasonally.
One gear rotates so slowly that it takes roughly 25,000 years to complete a single revolution. This nearly incomprehensible timescale shows just how precisely the mechanisms were engineered.
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