The patron saint of Murialdo is Saint Lawrence, celebrated on 10 August. The parish church dedicated to him, in the hamlet of Ponte, was rebuilt in 1445 to a design by master Francesco Garone, who adapted a pre-existing 14th-century building, later reworked in Baroque style: surviving from the original construction are the ogival portal with small columns, the Gothic terracotta rose window on the façade and the tall spired bell tower. It was precisely this renewal, in 1445, that drew the ire of neighbouring Calizzano, an ally of the Republic of Genoa, which sacked the town in revenge; the Genoese doge Giano Fregoso himself recorded in writing how hostile Murialdo had been.
From 1347 the town became part of the feudal domains of the Del Carretto family, who enlarged the local castle; in 1434 the men of Murialdo obtained numerous privileges from Marquis Galeotto Del Carretto in exchange for their loyalty to the Del Carretto cause. The castle, rebuilt in the 14th century, was finally destroyed in 1533 by order of Gerolamo Sacco, governor of Ceva.
