The Rock Engraving Park of Grosio was founded in 1978 with the aim of a preservation and valorization of the historical, archeological, architectural and landscape heritage of the Castle Hill (Dosso dei Castelli), based upon the donation of land property and two medieval castle ruins by the Marquess M. Pallavicino Mossi Visconti Venosta. Impressive and silent remain the ruins of the Old Castle (Castello di San Faustino) from the 10th-11th century on the Castle Hill, contrasted by the New Castle (14th century) that dominates this hill between the Adda Valley and the Roasco River at the entrance to the Grosina Valley. Next to them on the surface of the Rupe Magna, an imposing rock of characteristic whale shape, more than 5.000 petroglyphs from the 4th to the 1st millennium BC can be found.
The small excavation museum (Antiquarium) which is located in the Ca’ del Cap informs about the results of the archaeological excavations of two protohistoric settlements from the 16th to 1st century BC on the Castle Hill and the neighboring Giroldo Hill.
The park is managed by a Local Government Association (Province of Sondrio, Comunità Montana di Tirano and the municipalities of Grosio and Grosotto) and works in close collaboration with the State Authority for Archaeological Heritage of Lombardy (Soprintendenza per i Beni Archeologici della Lombardia).