Monumento naturale regionale di Preia Buia

The Preia Buia natural monument consists of three erratic boulders made of serpentine rock, situated in a wooded area near the San Vincenzo Oratory. These boulders vary in size and display distinctive green-tinted surfaces worn by time.

The boulders were transported to this location during the last glaciation of the Quaternary period by moving ice sheets. The carved symbols on the rocks demonstrate that people used this site for rituals during prehistoric times.

The largest boulder carries many carved symbols and cup marks that suggest its former use as a sacred place for ancient rituals and gatherings.

The site is part of the Ticino Valley Natural Park and is reachable on foot via local hiking trails. Visit with sturdy footwear since the ground can be uneven and damp due to the wooded surroundings.

The serpentine stone exhibits magnetic properties that can interfere with compass readings and cause them to point in wrong directions. This rare characteristic makes the site interesting for anyone curious about geological features.

Location: Sesto Calende

Inception: May 22, 1984

Part of: Natural Park of the Ticino Valley in Lombardy

GPS coordinates: 45.73608,8.62738

Latest update: December 9, 2025 20:24