Piglio is a comune (municipality) in the Province of Frosinone in the Italian region Lazio, located about 50 kilometres (31 mi) east of Rome and about 30 kilometres (19 mi) northwest of Frosinone, offering a panoramic view on the valleys of the Sacco and Aniene rivers.

It has been identified with the ancient Roman Capitulum, a Hernican town.

In 1347 it was captured by Cola di Rienzo and, from the late 14th century, it was under the Colonna family, who held it until 1816.

Piglio became part of the newly formed Kingdom of Italy in 1870.

During World War II, it was bombed by Allied planes, which destroyed about 30 percent of the edifices.