The formation of Tuscania begins in the final bronze phase (before the XII century BC). From the VII century BC. seven villages, identified by their respective necropolises, stood near the present Colle San Pietro.  Their aggregation in the constitution of a single center took place very slowly, so that it can be said accomplished only in the IV century BC.


During the archaic phase, VII - VI century, Tuscania was part of the territory of Tarquinia, whose influence is evidenced by the type of tombs, while relations with Greece are highlighted by the pottery found in the Scalette necropolis.


The golden age of Tuscania goes from the IV to the III century BC. With the spread of the sarcophagi in nenfro (a variety of gray tuff), while the city begin to form around the San Pietro hill and the Rivellino castle. Romanization begins from 285 BC. and apparently occurs in a peaceful way, facilitated by the via Clodia which crossed the whole Etruria, from Veio to Saturnia. After the fall of the Roman Empire, Tuscania became part of the Lombard kingdom.


Then because of the battles between Guelphs and Ghibellines, numerous castles were built in the area. But in the 1300s due to famines and the black plague, Tuscania became depopulated turning into a modest center of the Papal State. In the sixteenth and seventeenth centuries, during a period of relative peace, the production of cereals and the bovine and sheep breeding promoted the development of the local economy, so that the wealthy land and cattle owners built their late-Renaissance palaces in the city.


In 1870 the Kingdom of Italy replaces the Papal State, inheriting a city that is no longer as flourishing as it used to be, yet decent. In recent times the event that indelibly marks Tuscania was the destructive earthquake of February 6, 1971, which caused the collapse or injury of numerous buildings, including the splendid Romanesque churches of San Pietro and Santa Maria Maggiore, later excellently restored.