The Castle of Santa Maria, better known as Castellaccio (Castelasc in dialect) stands in a dominant position on the Orobic side, surrounded by apple orchards. It was built by Ludovico il Moro at the end of the 15th century and represented, together with the city walls which are still partly visible, the defensive system of the village against possible incursions by the Grisons who, wishing to expand their dominion south of the Alps, were putting increasing pressure on the northern borders of the Milanese lordship of the Visconti family (from 1335 it also included Valtellina and Valchiavenna).From the ruins of Castellaccio, moreover, the view of the city, of the vineyards on the opposite side and of the mountain (where you will recognize, in the middle of the sea of trees, the hamlets of Roncaiola and Baruffini) is really very beautiful!