Pienza is a town and comune in the province of Siena, Tuscany, in the historical region of Val d'Orcia. Situated between the towns of Monteā¦Pienza is a town and comune in the province of Siena, Tuscany, in the historical region of Val d'Orcia. Situated between the towns of Montepulciano and Montalcino, it is considered the "touchstone of Renaissance urbanism".