The Praze Orloj, installed on the Old Town Hall, is the oldest still-operating astronomical clock. Its astronomical dial shows an Earth-centered cosmos with the Sun orbiting Earth (medieval Ptolemaic model). It displays Old Czech time, Babylonian hours, sidereal time, zodiac position, and Moon phases. Every hour, Death (a skeleton) rings his bell, Vanity admires a mirror, Greed shakes his purse, and the Turk shakes his head—then the twelve apostles process through windows above.