It's called an astrarium and originally had an astrolabe, and calendar dials. The first was created in 1344 by scholar and physician, Jacopo de 'Dondi, but destroyed in fighting with Milan in 1390. The original had figures that moved to show the lunar aspects to the Sun. The Zodiac is complete except for Libra, with its symbol the Scales. The story is that it was left out by guild workers who felt they were unfairly treated by the city commissioners.


