The town's name appears for the first time in a donation dated 883, with which the Lombard prince Sichard granted the abbess of S. Sofia a property located in "Lions" (Lioni). The ancient settlement was probably one of the smaller neighboring towns of Ferentino, a
Samnite stronghold destroyed by the Romans during the
wars between these two peoples. The remains of Cyclopean walls typical of Samnite fortified villages were found on mount Oppido between Lioni and Caposele. The walls encompassed an area large enough to hold houses, barns, and land for pasture. Numerous clay fragments, primarily from tiles and pottery, were found inside the walled area of Oppido. In addition, the town contains foundations of a large building whose layout resembles a medieval castle, and thus suggests continued use of the site in medieval times. ==Twin towns==