The Old Town (Prague) Astronomical Clock is a medieval astronomical clock showing not only the time and date, but also the position of the Sun, phases of the Moon, astronomical cycles and holidays of the Christian calendar.

The astronomical clock is located on the south side of the tower of the Old Town Hall in Prague. The first historically documented mention of the astronomical clock is found in a document dated 9 October 1410.

It is the last technical monument in the world still capable of measuring Babylonian (sidereal) and Old Czech time. It shows the movements of cosmic bodies and every full hour the astronomical clock is animated by marching figures of the apostles above the astronomical dial and moving statues on the sides.

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