Terni [ˈtɛrni] About this sound listen (Latin: Interamna Nahars) is a city in the southern portion of the Region of Umbria in central Italy. The city is the capital of the province of Terni, located in the plain of the Nera river. It is 104 kilometres (65 miles) northeast of Rome.Originally founded as an Ancient Roman town, the city has changed across the centuries.During the 19th-century, steel mills were introduced and led the city to have a role in the second industrial revolution in Italy.