There is a hidden art masterpiece in the very centre of Florence that most of the tourists don’t see. Actually, it’s so hidden that even many people from Florence don’t know it. I bumped into by chance when, a few years ago, I was taking a Saturday morning stroll with my friends. We saw an open gate leading to a Cenacolo (a fresco representing The Last Supper) painted by the very important renaissance artist Domenico Ghirlandaio. Before getting to the fresco, we passed through the nice cloister of a small monastery and I remember we were astonished both by its beauty and by the fact that we had no idea such a place existed (and it was in a part of the town we knew so well!).
If you like art or just need to take a break from mass-tourism, I really recommend this spot. Entrance is free of charge (but you can leave a donation), open only on Mondays and Saturdays from 09:00 to 13:00.