Narni (Latin: Narnia) is an ancient hilltown and comune (municipality) of Umbria, in central Italy, with 19,252 inhabitants (2017). At an altitude of 240 metres (790 ft), it overhangs a narrow gorge of the River Nera in the province of Terni. It is very close to the geographical centre of Italy. There is a stone on the exact spot with a sign in multiple languages.

The area around Narni was already inhabited in the Paleolithic and Neolithic Ages, as attested by finds in some of the caves. Around the start of the first millennium the Osco-Umbrians, a people with a language of Indo-European origin that dominated the left bank of the Tiber that vertically cuts the region to the Adriatic Sea, settled in the area and called the town Nequinum. Records mention Nequinum as early as 600 BC.

The Romans conquered Nequinum in the 4th century BC and made it a position of force at a key point of the Via Flaminia, the famous road which connected the city of Rome to the Adriatic Sea (at that time the road passed through the town descending to the right bank of the Nera to then carrying on to Carsulae, Acquasparta, Massa Martana and Spoleto). It supported the Gauls with the hope of freeing itself from Rome. The attempt failed and the victorious Romans changed its name to Narnia after the nearby Nar River; as in the case of Benevento, the former name was considered of ill augury— in Latin: nequeo means 'I am unable', and nequitia means 'worthlessness'.

During Roman times the town was a strategic outpost for the Roman army. In 299 BC it became a Roman Municipality and took the name Narnia. The rediscovery, in the late 20th – early 21st century, of an ancient Roman shipyard within its territory has made researchers hypothesise its particular importance during the Punic Wars. In 209 BC, however, Narnia refused to help the Romans financially with their aim of continuing the war against Carthage.

The Roman Emperor Nerva was born at Narni in 30 AD.

Narnia is mentioned in an Early Christian list of "false gods" in the second century Church father Tertullian's Apologeticus, midway into Chapter 21:

Not even a human being would care to have unwilling homage rendered him and so the very Egyptians have been permitted the legal use of their ridiculous superstition, liberty to make gods of birds and beasts, nay, to condemn to death any One who kills a god of their sort. Every province even, and every city, has its god. Syria has Astarte, Arabia has Dusares, the Norici have Belenus, Africa has its Caelestis, Mauritania has its own princes. I have spoken, I think, of Roman provinces, and yet I have not said their gods are Roman for they are not worshipped at Rome any more than others who are ranked as deities over Italy itself by municipal consecration, such as Delventinus of Casinum, Visidianus of Narnia, Ancharia of Asculum, Nortia of Volsinii, Valentia of Ocriculum, Hostia of Satrium, Father Curls of Falisci, in honour of whom, too, Juno got her surname.

In Late Antiquity it suffered the events of the Greek-Gothic War (535–554) and was plundered by Totila. Narni was contested by the Exarchate of Ravenna and the Lombard Duchy of Spoleto in the late sixth century as the city controlled the southern reaches of the Via Flaminia, an essential route between Rome and Ravenna. Narni was the seat of a Lombard gastald. In 755 Fulrad went to "Rome carrying the keys of these towns, which he handed to the Pope{{nbs"...: Ravenna, Ariminum, Pisaurum, Conca, Fanus, Caesenae, Senogalliae, Esium, Forum Pompilii, Forum Livii, Narnia and others}}. During the late 9th to early 10th century, Narni was, along with much of central Italy, a stronghold of—or threatened by—the Saracens. Narnia embraced the cause of Otho I of Saxony thanks to the mediation of its bishop, by then Pope John XVII.