If you wish to explore Tuscany then having Florence as your base is a good idea. You can either rent a car that will give you the possibility to explore all the surrounding areas at your own pace or if you don’t feel confident enough to drive around in a foreign country then you can just use the train or organized bus excursions. On our fourth day in Italy we booked a full day tour to visit Siena and San Gimignano. (Check out this post: Tuscany itinerary for one week)
I had booked the trip through Viator although when I arrived to Florence I had found a booklet of another travel agent that actually offers a better package that included an actual visit to a winery in Chianti and lunch (not included in the Viator package).
The first visit was to the Basilica of San Domenico which is also known as the Basilica Cateriniana and is the most important church in the city. Unfortunately no photos were allowed inside. 
The tour also included a visit to the Piazza del Campo which is the historic center of Siena and is regarded as one of Europe’s greatest medieval squares. The square is constructed in a shell-shape where visitors sit around to enjoy the surrounding beauty. The center is full of restaurants and cafes as well as souvenir shops. This is where the famous Palio horse race takes place twice a year
The guide then took us to the Contrada della Selva which is a museum inside the Church of Saint Sebastian built in the end of the 15th century. It is actually a ritual that the horse of that Contrada enters the Church to be blessed before the Palio race. Siena also has a smaller version of the Duomo like the one in Florence, known as the Siena Cathedral. It has the form of a Latin cross with a slightly projecting transept, a dome and a bell tower. The exterior and interior are constructed of white and greenish-black marble in alternating stripes, with addition of red marble on the façade. Afterwards we had some free time to enjoy a light lunch at the Piazza del Campo before heading to our next destination, San Gimignano.
The drive to San Gimignano was approximately 40 minutes and the visit was short but sweet! San Gimignano is a small village in the province of Siena and is also known as the Town of the Fine Towers. It is a UNESCO World Heritage Site famous for its medieval architecture. The tour consisted of a visit to the San Gimignano 1300 museum which exhibits a ceramic recreation of the city as it existed in the 1300. The Museum is the culmination of the vision of two Master Artists, Michelangelo and Raffaello Rubino who, together with a team of artisans and historians, have faithfully recreated San Gimignano as it once existed. Here you could taste some wine and purchase a bottle or more to take back with you. Afterwards we had some free time to explore the city, which is really a masterpiece. I wish we were given more time to explore the city, that’s why if you are travelling alone you can definitely spend at least half a day walking around the cobbled streets.
