Bottom two are Florence. The left one should need no introduction. Captured in the moments before he slings Goliath. The right is the Duomo from outside the Baptistry.
My first time in Italy and I wish I had gone sooner. If you get the chance, go. Za Za's near the Central Market in Florence was the eating place of choice. The food in the market was pretty good, too. Needless to say the beer and the wine is very quaffable.
Particularly in Florence, you cannot turn around without seeing something famous from history. Venice is a truly unique place in the world. Which may account for the vast number of tourists.