Forty-five minutes to an hour away from Florence awaits the medieval hilltop town of San Gimignano, a UNESCO World Heritage Site. Bordered by 13th-century walls and featuring a triangular central square lined with historic houses, the town is best-known for its "skyline" of medieval towers and its 12th-century church with frescoes by Ghirlandaio.
The town is popular with tourists, who arrive in packs by bus, so it can be difficult to navigate the old town in the afternoon. While they are scouring the sites, I suggest following the city walls to the opposite side of the entrance, where the walls are slightly crumbled. Here you will see sweeping views of the famous Tuscan countryside, with its hills dotted with vineyards, old villas, and olive trees.
Few visitors venture outside the city walls, but I recommend it. Be adventurous and you'll find signs of the city that once was. The ruins have been overrun by nature, with olive trees running along walls that once saw the plague, and hidden steps leading you to views of the city against a backdrop of green.