Prague Astronomical Clock, Prague

Set into the Old Town Hall’s southern wall, Prague Astronomical Clock is a medieval astronomical clock. Its documented existence reaches back to the ninth of October, fourteen ten. The clock ranks as the world’s third-oldest astronomical clock and the oldest still running.

The large astronomical dial is a mechanical astrolabe, presenting the Sun and Moon’s place in the sky from an Earth-bound view. The dial’s moving rings and symbols pack a medieval model of the heavens into a facade. Below, the calendar face gives the month, day, and fixed Christian feasts.

Small windows above the dial carry the moving Apostles; a rooster figure provides sound from the upper part of the display. Fire during the Prague Uprising caused severe damage, but repairs brought the mechanism back into service in nineteen forty-eight.