It is the oldest functioning Astronomical Clock in the world dating back all the way to the year 1410. Prague Astronomical Clock was installed in the last decade of the Bohemian Golden Age under the reign of Charles IV.
It is widely accepted nowadays that the Prague Clock was constructed by a royal clockmaker Mikulas of Kadan, as opposed to the popular belief that the creator of the mechanism was Master Hanus. This assumption is a product of a legend developed by the writer Bohuslav Balbin, who wrote that Master Hanus was blinded so he couldn't recreate the Astronomical Clock anywhere else.
Prague Astronomical Clock shows four different times known as Old Czech time, planetary hours, sidereal time and "German" hours. Which one shows the current hours? The latter one illustrates the current time since mid-16th century. "German" hours are marked with 24 golden Roman numerals along the circle of the astrolabe. You can also find old numerals on the outer frame of the clock dial that indicate Old Czech Time counted from the dawn. It was brought from Italy by the Holy Roman Emperor and Bohemian King Charles IV.
The unique mechanism of the Prague Clock not only shows us what time and day it is, but also tracks the movement of celestial bodies, or planetary hours, like the Sun and Moon. Depending on their position, predictions of upcoming events were made. People would even decide when to receive popular medical treatments such as bloodletting based on that!
The last time system was added in 1865 for the astronomical purposes. Sidereal time rotation lasts 23 hours and 56 minutes.
There are also four figurines on the side of the clock dial or astrolabe. They symbolise allegories of Death, Greed, Lust and Vanity. The figurines move their heads and hands when the clock rings to signalise every hour from 9am to 11pm. They are joined by 12 Apostles and a Golden Rooster whose crow ends the procession and the movement of the allegories. Don't miss the show!