This link takes you to specific directions via Google Maps driving from Rome: http://bit.ly/1Ms5Sef or this one from the Bari airport http://bit.ly/1Ms5Sef

Once you are in Terlizzi, follow any signs leading to MercatoneUno. It is a large department store near the villa. That will get you on Strada Provincaiale 108. Follow this road going to Mariotto. Eventually, you drive across four speed bumps in the road (you will hear a short chopping/rattling sound as you drive over them, not big "mound" speed bumps), after the fourth speed bump/rattle, take an immediate 90 degree hard right. You will see a pine tree-lined street. That is Via Appia and Villa Cappelli is about 200 meters in on your left.