Terni (/ˈtɛərni/ TAIR-nee; Italian: [ˈtɛrni] ⓘ; Latin: Interamna (Nahars)) is a city in the southern portion of the region of Umbria, in Central Italy.

[4] Interamna was founded as an Ancient Roman town, albeit settlements in the Terni area well precede this occurrence.

The city was founded around the 7th century BC by the Umbrians Nahartes, in a territory inhabited (as testified by archaeological excavations) as early as the Bronze Age.

In the 3rd century BC, Terni was conquered by the Romans and soon became an important municipium lying on the Via Flaminia and known under the name Interamna, meaning "between-two-rivers".

In 271 BC the Roman consul Manius Curius Dentatus ordered the construction of a canal (the Curiano Trench) to divert the water from the marshes in the Rieti Valley and from Lake Velino over the natural cliff at Marmore, creating the waterfall.

As with many of the Italian communes of the Late Middle Ages, it was beset by civil unrest between the partisans of the Guelphs and Ghibellines, and later between the Nobili and Banderari (Terni's bourgeoisie).

In 1580, an ironwork, the Ferriera, was introduced to work the iron ore mined in Monteleone di Spoleto, starting the traditional industrial connotation of the city.

The presence of important industries made the city a favorite target for the Allied bombardments in World War II.

On August 11, 1943, a raid by 44 USAAF bombers, which dropped 213 tons of bombs, devastated the city, killing 564 people.