The territory of San Casciano in Val di Pesa, already inhabited in Etruscan times, owes its fortune to the presence of the Roman road which connected the colonies of Florentia (now Florence) and Sena Julia (Siena). The locality was situated at the tenth mile from Florentia and the name of San Casciano a Decimo is mentioned in several medieval documents.
In 1343, Gualtieri di Brienne, Duke of Athens, came to power in Florence and, realizing the strategic importance of San Casciano, began work on its fortification. Due to the importance attributed by the Duke to the place, the name of the town was changed to Castel Ducale. When the work was suspended after the expulsion of the Duke, Florence finally decided to build walls around the town, wall converting it into an impregnable castle.
The repopulation of these areas, traversed by a dense network of roads, is marked by the presence of four parish churches, on which many suffragan churches depended. The parish church of Santa Cecilia a Decimo, documented in 1043, gradually lost its importance with the transformation of San Casciano into a fortified urban centre, becoming a simple church in 1797.
From the parish church of San Giovanni in Sugana come numerous art works now kept in the San Casciano Museum, while the parish churches of San Pancrazio and Santo Stefano a Campoli still preserve some paintings dating from the 16th and 17th centuries.