The world clock of Jens Olsen or Verdensur is a modern astronomical clock, which is exhibited at the Copenhagen City Hall.
The watch was designed and calculated by Jens Olsen (1872-1945), who was an experienced locksmith but later learned watchmaking. He was also involved in the beginning of the clock construction, but died in 1945, 10 years before the clock was built.
The watch consists of 12 movements, which together consist of 15448 parts. The watches are mechanical, they must be wound once a week. In addition to time, the screen displays lunar and solar eclipses, the position of stellar bodies and the perpetual calendar. The fastest transmission takes place every ten seconds, while the slowest one takes place every 25,753 years.
The clock was calculated until 1928, after which it was headed by the astronomer Professor Alice Stromgren. The clock drawings were made between 1934 and 1936, and the actual production took place from 1943 to 1955. The clock was launched on December 15, 1955 by King Frederick IX and Jens Olsen, the younger granddaughter of Birgit.