The so called Castellaccio is an old fortified building, part of the ancient Bagnacavallo stronghold. It dates back to the XII century, even if the current structure has clear XV century features. Now is a private propriety.The imposing building has a brick facade with a socle marked by a rounded frame; on the top, at the corners machicolations are still present. The main door with a round arch leads to the entrance hall which then leads to the ground floor rooms, some of which are decorated with XX century frescoes. Another door leads to a wide inner yard with some smaller buildings used as store rooms and for other purposes.