On the hills between Siena and Pisa are three small medieval towns , as well as wonderful views of their small districts and squares are not to be missed unique panoramas .
San Gimignano is famous for its tower houses and the excellent Vernaccia (white wine ) , while Volterra is famous for its alabaster, with which local craftsmen produce real art objects .
Certaldo is the smallest of the three countries , famous for being the birthplace of Giovanni Boccaccio ‘s Decameron writer, and its festival of street arts held in summer : Mercantia .