On your way to the Sistine Chapel you'll be pushed by throngs of people through the Vatican Museum's map gallery. I love maps, and these are not only fascinating in their detail, but in their accuracy as well, considering they were commissioned in the late 1500s. Here is a surprisingly detailed map of Venice.
How accurate where these 16th century maps drawn by Ignazio Danti? Well, I've taken a map of Italy's Garfagnana region (northern Tuscany) and compared the accuracy of the placement of cities with a modern map. Interested? See the results: How accurate are the towns represented in Danti's map of the Garfagnana?