The building, named in the fifteenth century Grancia Rupta, stood in an open and poorly inhabited plain. The grancia was a fortified farm where the products of the estate were collected. Following the restoration of the eighties, the stronghold revealed its fifteenth-century structure. It has the shape of a quadrilateral with a large internal courtyard and central cistern, a chapel with an ogival vault, a mighty watch-tower, a convent wing with a representative room, a cellar, stables, warehouses, and basements. The main front is characterized by the arcade tower, with the entrance portal surmounted by the Valperga coat of arms (a twig with the goat), which divides, on the left, the part with the first floor and rectangular windows with pointed arches on which extend the service rooms, and, on the right, the less extensive factory with the chapel and other rooms.