Coming from Greve there are two roads back to Florence. One goes through Strada in Chianti and the other goes through Passo dei Pecorai, Ferrone, and Tavarnuzze. You need to take the one that goes through Passo dei Pecorai, etc. Just after the town of Tavarnuzze you will arrive at a roundabout where I will meet you. If you don't get lost it is a one hour drive from Greve to the Certosa Exit.