The hilltop ruins above the village are what remains of the Del Carretto castle, built in the 13th century when the marquises fortified Dego and ran a mint here. The walls were knocked about repeatedly in the centuries that followed — by Genoese, Spanish and finally Napoleonic forces during the 1796 battle — and the building was never rebuilt.
What survives is the curtain wall and parts of the keep, accessible by a short footpath from the centre. The view from the top runs across the Bormida valley to the Ligurian Apennines and gives a clear sense of why the position was held for six centuries.