The Prague Astronomical Clock 

The Prague Astronomical Clock or Prague Orloj.
The clock mechanism itself is composed of three main components: the astronomical dial, representing the position of the Sun and Moon in the sky and displaying various astronomical details; "The Walk of the Apostles", a clockwork hourly show of figures of the Apostles and other moving sculptures-notably a figure of Death (represented by a skeleton) striking the time; and a calendar dial with medallions representing the months.