Designed as a "mathematical ornament" for the Museo Galileo, the sundial shows the true solar time of the place in which it stands. The hour and the date are indicated by the shadow of the glass globe atop the great bronze gnomon. The hours are indicated by radial brass lines set into the pavement, while the date is indicated by transverse lines of travertine showing the daily path of the Sun as it enters the signs of the zodiac.