Castell de Montfalcó d'Ossó crowns a hill at 389 meters elevation in Ossó de Sió, Urgell, commanding views from the eastern foothills of the Almenara mountains. Founded around 1070 by Count Ermengol IV of Urgell, the fortress features a square medieval tower dating to the 12th or 13th century, representing the oldest preserved remnant. By the 16th or 17th century, the castle lost its defensive function and was transformed into a seigniorial palace with Romanesque architectural elements from the 10th to 12th centuries. Later held as a possession of Poblet monastery and subsequently by the barons of Montbui, the site preserves significant layers of medieval and Renaissance architectural heritage.
