The Grotte dell’Arco (Arch Caves) are located in the Pantano area, about 3 km from the centre of Bellegra, on the slopes of the Montagna di Roiate. They are the only underground karst cavity in the whole province of Rome and one of the most important karst phenomena in Lazio, so significant that the area has been designated a Special Conservation Zone (code IT6030036).
The cave extends for almost 1,000 metres, with a 23-metre difference in elevation between the entrance and its furthest point upstream, and in some sections the vaults reach 30 metres in height. A small stream runs through it, forming pools of clear water, and the walls are rich in stalactites, stalagmites, columns and other concretions. The name comes from a rock arch visible near the entrance, evidence that the cavity has been visited since ancient times.
First explored and surveyed in 1925 by the Circolo Speleologico Romano, the cave yielded in 1999 two groups of prehistoric rock paintings, dating from the late Neolithic to the early Bronze and Copper Age (around 4000-3000 BCE), along with paleontological remains: a discovery unique in the entire Apennines, suggesting a ritual use linked to the worship of water.
The route is divided into three sections: the initial galleries (the 190 m muddy passage and the 80 m second gallery), the middle section with large chambers such as the “salone ciclopico” and the “sala del duomo”, and finally the terminal section, reserved for expert speleologists. The first section is fitted with a walkway and lighting and can be visited, including by people with disabilities, through guided tours organised by the municipality, generally from April/May to November on weekends.
Nearby is also the Pertuso di Roiate, a 240-metre natural tunnel running through a small hill.
Opening hours and contacts
The caves can only be visited on a guided tour:
- in season (roughly from May to early October): Saturdays and Sundays from 10:00 am to 5:00 pm, with tours leaving about every hour;
- the rest of the year: by booking only.
Phone for bookings: +39 351 527 5501
Email: grottedellarco@gmail.com
The calendar changes from year to year: before setting off, it is best to phone and confirm days and times.
Source: Pro Loco di Bellegra (checked in October 2026).
For information and bookings:
- Official website of the Grotte dell’Arco
- Le Grotte dell’Arco a Bellegra - VisitLazio
- Grotta dell’Arco - Bellegra - ParchiLazio
- Grotta dell’Arco - Comune di Bellegra
- Grotte dell’Arco a Bellegra - Lazio Nascosto
- Grotta dell’Arco di Bellegra - Sotterranei di Roma
- Grotta dell’Arco di Bellegra - Lazio Eventi
- Grotte dell’Arco - Bellegra - TripAdvisor
- Alla scoperta delle grotte dell’Arco di Bellegra (Italian)
- Grotta dell’Arco - Wikipedia
Photo: topographic survey of the cave, Giovanni Mecchia, Marco Mecchia, Maria Piro, Maurizio Barbati (2003), Wikimedia Commons, CC BY 4.0.
