The planetary clock by Pietro Fanzago, a well-known engineer and skilled bell founder, was commissioned in 1580 by the Council of the Valley. Located in the civic tower and surrounded by frescoes, the clock requires the observer to orient themselves with respect to the Sun, the Moon and the Earth. The eight winged heads represent the four cardinal winds and the four solstitial ones. The Rose of the Winds is formed by the convergence of the wind lines towards the centre. The hour ring is 71.5 cm wide and marks the 24 hours of the day with Roman numerals. The arrows indicate half-hours and quarter-hours, while the large index marks the time. The movable part includes three concentric crowns: the first represents the months of the year, the signs of the zodiac and the duration of day and night; the second indicates the days of the Moon and the third represents the starry sky.