The Prague Astronomical Clock or Prague Orloj is a medieval astronomical clock located in Prague, the capital of the Czech Republic. The Orloj is mounted on the southern wall of Old Town City Hall in the Old Town Square and is a popular tourist attraction. It 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; and a calendar dial with medallions representing the months.