The Astronomical Clock of Prague, also known as the Prague Orloj, is a medieval clock located in the Old Town Hall of Prague, Czech Republic. It was installed in 1410, making it the third oldest astronomical clock in the world and the oldest one still in operation. The clock features a unique combination of a mechanical clock, an astronomical dial, and various moving sculptures. Every hour, the clock puts on a show with figures that include the Apostles and other symbolic representations. The clock not only tells the time but also indicates the position of the sun and moon, along with other astronomical details, making it a remarkable piece of engineering and art.