The Monti Simbruini are a mountain range in central Italy, a part of Apennines mountain system.
The 'Simbruini' name derives from Simbruvium, a lake formed by the river Anio, situated in the territory of the Aequi; it may derive from Latin sub imbribus ("under the rain"). They are also popularly known as "Rome's Alps".
The Monti Simbruini mark a part of the border between Abruzzo and Lazio. The Monti Simbruini border with the Monti Cantari and the Carseolani Mountains. The range's highest peak is Monte Cotento, at 2,015 metres (6,611 ft) in elevation.
The headwaters of the River Aniene are in the range. The Liri river, one of the main Italian rivers, also originates in the mountains (Petrella Liri).
On the Lazio side of the mountain range, between the provinces of Rome and Frosinone, a natural park has been established, the Parco naturale regionale Monti Simbruini.
The Regional Park of the Monti Simbruini, which also includes the Monti Cantari range, was established in 1983. It has an area of 300 square kilometres (120 sq mi).
The regional park and mountains include the comuni (villages) of: Camerata Nuova, Cervara di Roma (Campaegli), Filettino, Jenne, Subiaco (Monte Livata), Trevi nel Lazio, and Vallepietra.
Habitats in the Monti Simbruini include: the Apennine deciduous montane forests ecoregion, in the temperate broadleaf and mixed forests biome; and the Italian sclerophyllous and semi-deciduous forests ecoregion, in the Mediterranean forests, woodlands, and scrub biome.