The patron saints of Piana Crixia are the martyrs Eugene, Victor and Corona, celebrated on 24 April. The parish church dedicated to them, in the hamlet of Borgo, was built over the remains of a Roman-era chapel and originally depended on the abbey of San Salvatore di Giusvalla, then, after the latter's destruction, on the abbey of San Quintino di Spigno Monferrato: it was rebuilt in Baroque style between 1733 and 1766, together with the bell tower, with a Greek-cross interior.
The town also preserves other historic churches, including that of San Colombano in the hamlet of Lodisio and that of San Massimo, whose assets belonged in medieval times to the same abbeys of Giusvalla and Spigno Monferrato: only in 1823 did the religious community of San Massimo become independent of the parish of San Colombano. The municipal territory today lies partly within the Piana Crixia regional nature park.
