18. The heretical clock
Another thing I don't know about this clock, and this fact would be very helpful to know, is exactly when it was built. Why? Because the sun is in the centre of the clock face, with a much smaller orb towards the pointy end of the 'hand'. Every day, everyone who looked at this clock would be seeing a smaller 'planet' revolving around the sun at the centre of its 'universe'. This was a dangerous statement to be making in the Holy Roman Empire during certain parts of the middle ages.
If the clock was built after Galileo was forced by the Holy See in 1633 to recant his claim that the earth revolved around the sun and not vice versa, this clock would have been suggesting heresy every day for the next 125 years until the restriction on Galileo's theories were lifted. If it predated Galileo, then the clockmaker was a very well informed craftsman to know of the heliocentric theories of Copernicus which were not published until the year of his death in 1543, 90 years before the ban on Galileo.
The first church to stand on this spot was built in the 5th century, making it the oldest known church in Venice, but the present church is much later than that, and so is the clock. Could the clock have been built as recently as post 1758, when it was no longer heresy to say that the earth revolved around the sun? I don't think so. The unusual non-standard layout of the face would suggest that this is a very old clock as clocks go. Could it have been pre-1543? If so, the sun-with-revolving-planet design would have to be just an accidental coincidence, which seems improbable. The most likely date for the age of this clock would therefore seem to be somewhere between Copernicus and Galileo, around 1543-1633.
Unfortunately, that leaves us with another puzzle. If the clock was proclaiming heresy on a daily basis after 1633, why was it not destroyed while those ideas were banned? Venice was a very independent power at that time, not known for its obedience to papal authority, and so a papal edict about the solar system might simply have been ignored. But I suspect we'll never know.