The town centre stands on a small hilltop, commanding from the southern edge the wide Rieti valley, at the bottom of the Sabine hills and of monti Reatini, including mount Terminillo.

The town itself underwent significant development, being re-organised according to typical Roman urban standards (e.g., two crossed roads make up the settlement's backbone), and was fortified with strong walls.

A stone bridge was laid across the Velino river, and a large viaduct was built to bring goods from the Via Salaria directly to Rieti's southern gate.

Roman Reate receives a number of mentions in Latin literature, thanks to its flourishing soil, its valued assets, and some peculiarities of the surroundings (such as wandering islands and hollow-subsurfaced fields).

Cicero, for instance, describes the tensions between Reate and Interamna (Terni) following the lake drainage, and refers to the country house (villa) that his friend Q. Axius owned in the plain.

[3] One of the most important Sabine families that gained success in Rome was the Gens Flavia, from which Emperor Titus Flavius Vespasianus (who started the building of the Colosseum, also known as the Amphitheatrum Flavium) descended.

After the fall of the Western Roman Empire Rieti suffered destruction by Barbarians, but never ceased to be an important gastaldate during the Lombard domination, as part of the Duchy of Spoleto.

As a favourite Papal seat, Rieti was the place of important historical events: Constance of Hauteville married here by proxy Emperor Henry VI (1185).

Moses ben Isaac of Rieti (1388–1467) was a Jewish scholar and physician who authored a two-part Dantean poem known for its wealth of literary-biographical information, and especially as a primary source for the Shalshelet haQabbalah of Gedalya ibn Yihya.

Only scarce remains were found during excavations in 19th and 20th century: the foundations of a large temple, the stone floor of the main square (forum), walls from private houses, concrete vaults, statues and pottery items.