Castelfranco di Sotto lies within the Pisa area, right in the heart of what is known as the "leather belt" - an area which, as the name suggests, is famed for its leather production. The city still has its ancient structure, which adheres to the precepts of an archetypal Roman castrum: two main roads meeting at the town centre, making for a city with four gates. It's like a nautical compass.
Castelfranco began to increase in industrial power in the second half of the twentieth century, especially for its shoemaking and other sectors in leather production. You still find many leatherworkers active in the town, whose work is exported all over the world.