メンタナの天然記念物・トップ5

From here on, it's a hike for experts. There are no CAI flags (or at least I didn't see any), nor is the trail clearly marked. There are only a few stone cairns, but it's mostly a matter of feeling. The return time is much longer than indicated.

Danger!!! the path is not calculated well!!! attention!!!! only for experts!!!!

The nature reserve extends over about a thousand hectares between the Tiber Valley and the Cornicolani Mountains, in the Roman Sabina. The landscape is hilly, with pasture areas, crops and fragments of woods, remnants of the original forests. The area is known for its botanical value and for karst phenomena such as caves and sinkholes, including the Pozzo del Merro, one of the deepest in the world. The reserve also preserves historical evidence, from prehistory to the Middle Ages.

Strada Bianca connecting via della Cesarina and via di Casal Boccone. The first stretch is a dirt road up to the bridge that crosses the ring road; then continues on a beaten path between cultivated fields. It ends with an easy singletrack up to Via Casal Boccone skirting the Almaviva building.

The Pozzo del Merro is a karst sinkhole located in the countryside north of Rome, between the Cornicolani Mountains in Macchia del Barco and Macchia di Gattaceca, in the municipality of Sant'Angelo Romano. According to initial studies by the University of Tor Vergata, the cavity is 392 meters deep, which is the maximum limit the measurements have reached. The probes launched since its discovery have not reached bottom, and the studies continue. This sinkhole has always been known to the locals. In 1890 it appears in the description of a tourist itinerary that leads from Rome to Sant'Angelo Romano, and is described as "a kind of chasm, at the bottom of which extends a small lake and whose very steep sides are covered with trees". https://www.sotterraneidiroma.it/sites/pozzo-del-merro

More than a trail marker, this ancient beech tree is a timepiece! Perhaps this is why some of its protruding roots protect a small improvised nativity scene. The "troscia" indicates the puddle of water that you come across on the path just south of the beech tree.

You can still follow the path by bike, but you pass in front of inhabited houses

The Reserve extends over a series of hills delimited to the west by the Tiber, to the south by the Bufalotta ditch, and to the north by the Rio del Casale which also marks the limit of the Municipality of Rome. The low rounded hills are still cultivated with extensive arable land or intended for grazing, while the slopes of the valleys are covered with scrub vegetation: these are the remnants of the oak forest (oak, oak, oak, downy oak and farnet) often accompanied by maples and elms . The fauna, threatened by urbanization and hunting until the establishment of the Reserve, is of extreme interest: the presence of mammals (fox, marten, weasel, but also badger and porcupine) is significant, among which that of the Italian hare stands out, an endemic Italian species. Of fundamental interest is the historical landscape system of the large estates (Marcigliana, Tor S. Giovanni), characterized by ancient farmhouses, often built on nuclei of Roman villas and by medieval towers that create a unique historical continuum. In this area stood the ancient Latin city of Crustumerium with its imposing defensive wall placed to control an ancient road route connecting Etruria and Campania.     Regarding access to the Reserve, we remind you that the public access accessible to all is via di Tor S. Giovanni n. 301, where there is Casale Lucernari, "Casa del Parco", and from where the circular route of the "Sentiero Natura" starts, while as regards the signposted accesses of via Nomentana/via della Cesarina; – via Salaria/via della Marcigliana; – via Salaria/via di Vallericca; – via della Marcigliana/via della Bufalotta; – via di Settebagni, these are accesses that lead to private properties and therefore passage must be requested from the owner, and correct, polite and respectful behavior must always be maintained for the environment, people and property assets. source: https://romanatura.roma.it/marcigliana#gsc.tab=0