The patron saint of Terzorio is Saint John Beheaded, celebrated on 29 August. The town's parish church, dedicated to the Nativity of Saint John the Baptist, was first built in 1444, only later reworked in Baroque style.
The tower of Terzorio, built in the 16th century thanks to the generosity of the inhabitants, has its upper part cut off at an angle and is still preserved in excellent condition: it was erected following the invasion of Barbary corsairs that struck the area in the 16th century. The town also preserves the oratory and chapel of San Sebastiano.
