The Meridiana is a sundial located in Piazza Vecchia, in the inner courtyard of the Palazzo del Podestà. This ancient sundial is engraved on a marble plate, and it was made in 1780 by the mathematician and astronomer Gian Antonio Calegari. The Meridiana of Bergamo shows the local solar time, based indeed on the position of the sun. It is a significant example of sundial, which was once one of the main instruments for measuring time before the advent of mechanical clocks.
The Meridiana is an attraction and a landmark for visitors wishing to admire this ancient instrument and to appreciate its precision in telling the time by using the sunlight. Built in the 1700s, it had the peculiarity of allowing the sunrays to filter through a slit (a hole) placed in a fixed shield on the arches above, and the reflection of the light would thus indicate the zodiac sign of that period, and the date.