Two distinctive wayside chapels, each on its rocky outcrop, stand on an ancient mule-track leading towards Calogna from the little village of Magognino.

While the first rock has one small cup mark, a round depression carved into the rock, the second rock, the one with the chapel of San Grato, has a concentration of over 250 cup marks of diameters varying from 3 to 5 cm and an average depth of 2 cm.

Nobody knows for certain what these prehistoric engravings signify, though there are a number of theories that they are associated with ancient religious cults.

The commanding position of these rocks over the lake allied to the astonishing number of the ancient engravings cut into them suggest that this place was already connected with religious practices in pre-Christian times.

Other interesting petroglyphs, mostly in the form of cup marks, can be seen along the mule-track, near the small church of San Paolo and along the path leading from Stropino to the top of the Motta Rossa hill.