Spello (in Antiquity: Hispellum) is an ancient town and comune (township) of Italy, in the province of Perugia in eastern-central Umbria, on the lower southern flank of Monte Subasio.

[3] The old walled town lies on a regularly NW-SE sloping ridge that eventually meets the plain.

Under the reign of Constantine the Great it was called Flavia Constans, as attested by a document preserved in the local Communal Palace.

The densely inhabited town, built with stone, retains its medieval aspect; the town is enclosed in a circuit of medieval walls built on Roman foundations, including three Roman Late Antique gates (Porta Consolare, Porta di Venere and the "Arch of Augustus") and traces of three more.

According to Professor Douglas Boin, who announced the discovery at an Archaeological Society of America meeting in early 2024, the temple dates to Constantine's period and marks the transition of the Roman Empire to Christianity.