Known as the Orloj, the astronomical clock was designed and built by the Imperial clockmaker Mikuláš of Kadaň and Charles University professor Jan Šindel. Consisting of three main components, the astronomical dial and the mechanical clock itself were first noted in a document on 9 October 1410. The third component – a calendar dial – was added around 1490 when the façade was decorated with additional gothic sculptures.

One of the most famous features of the clock is the hourly “Walk of the Apostles” in which carved figures of the Apostles appear in procession at two windows above the main ...