My three colleagues/friends and I had four wonderful and relaxing days in the super cute house - a former chapel, I assume - next to Costanza's family house. Costanza and her family were great hosts, very open, helpful and friendly.
The house is located on a hill in the woods about 15 min. by car from the city center of Florence. A car or a Vespa is recommendable and helpful for discovering the surrounded countryside or for grocery shopping. To go down to the city center a taxi is sufficient.
I highly recommend this Airbnb when in Florence as it is the perfect mix between enjoying the quite countryside and exploring the beautiful city of Florence. I will definitely come back soon.