The Monte de São Silvestre was populated from Recent Prehistory, when, at the base of its slope, this megalithic sepulchral monument was built, according to oral tradition.

A set of eleven granitic outcrops with rupestrian engravings were inventoried and studied, distributed over the east and east-southeast slopes of the mountain. These were designated by the toponym Breia. Breia is composed by a set of three horizontal outcrops and not very noticeable from the ground, located along a small valley, existing at the base of the eastern slope of Monte de S. Silvestre. There runs a water line that flows into the Nogueira River, one of the tributaries on the right bank of Lima. It is a place of natural window between the lands of the bottom of the valley and those of altitude, having been a traditional grazing area.

The outcrop is profusely recorded with Atlantic Art and other motifs from different chronologies having been divided into 7 different panels.

In general, the engravings are characterized by circular figures accompanied in certain places by semi-naturalist figures, with representation of the limbs in movement and the tail raised, for what appears to be an equine.