Riserva naturale di Monte Mario, Regional nature reserve in Rome, Italy.

Riserva naturale di Monte Mario is a regional nature reserve established in 1997 on part of Monte Mario, Rome's highest hill at 139 metres, covering 238 hectares. Within its boundaries lie Monte Cacciarello and several villas, including Villa Mazzanti, Villa Madama, Villa Miani and Villa Mellini, which houses the Rome Astronomical Observatory.

The site served as a residential area in Roman times and later attracted noble families who built their country estates here during the Renaissance. This pattern of occupation shaped the landscape over centuries.

Villa Mellini, constructed in the 15th century, contains an Astronomical Observatory and stands on the meridian line of Rome, offering scientific research facilities.

The reserve has several marked hiking trails through the forests with varying difficulty levels to suit different abilities. Visitors should wear sturdy shoes and allow plenty of time as some paths can be quite steep or challenging.

Monte Mario, the hill the reserve protects, is Rome's highest point at 139 metres, and the reserve covers 238 hectares of it, established in 1997. Within the protected area stands Monte Cacciarello, a secondary summit inside the park's territory.