The Septimontium was a proto-urban festival celebrated in ancient Rome by montani, residents of the seven (sept-) communities associated with the hills or peaks of Rome (montes): Oppius, Palatium, Velia, Fagutal, Cermalus, Caelius, and Cispius. The Septimontium was celebrated in September, or, according to later calendars, on 11 December. It was not a public festival in the sense of feriae populi, according to Varro, who sees it as an urban analog to the rural Paganalia.
The etymology from septem ("seven") has been doubted; the festival may instead take its name from saept-, "divided," in the sense of "partitioned off, palisaded." The montes include two divisions of the Palatine Hill and three of the Esquiline Hill, among the traditional "seven hills of Rome".