All of these maps are public domain from Wiki Commons. The first set shows the “big picture” (including Trieste). They may look fuzzy here, but the originals are not and can be easily sized with great clarity.
THE BIG PICTURE
VENICE / LAGOON
(This one is free to use but requires crediting source [Museo Vaticano])
This is the most famous, a woodcut by Jacopo di Barbari, 1500. A huge file of it can be downloaded and scaled. I used many extreme closeups in The Balloy Boy blog. It actually has just about every single building in Venice at the time.