I came back from a short vacation in Venice and Trieste the other week and took a lot of photos ~500) that I have just started to go through. Some can be found on my Flickr account. This completely random one shows a Truth Mouth or Lion's Mouth, which I thought was quite a funny concept.
There were a number of these spread out over Venice, before Napoleon came and removed them along with the old judicial system. They were used for denouncing other citizens by placing a signed note inside reporting a committed crime. Behind is a kind of mail box emptied by officials. The case would then be tried and if the accused was found guilty, the reporter would be rewarded. If found not guilty, the reporter would be punished instead, with the same punishment as the accused would have gotten. This special Lion's mouth (without the lion motive) inside the Doge's Palace was to be used against corruption or tax evasion amongst politicians or officials of the Republic.
The text apparently says: "Put down here your Secrets, against those who oppressed you, freely and officially. Have faith, for those who hide the truth will answer for it."