The patron of Arvier is Saint Sulpicius, celebrated on 17 January in the parish church dedicated to him, recognisable by its Romanesque bell tower. Not far away, overlooking the valley floor atop a rocky outcrop, stands the chapel of Rochefort, where until the 19th century the remains of the castle of the same name could still be seen.
Arvier's monumental heritage also includes the remains of the castle of La Mothe, dating from the late 13th century, the castle of Arvier at Grand-Haury and the fortified house of Planaval, in Valgrisenche, the highest-altitude casaforte in the Aosta Valley. Among the most striking ruins in the municipality are also those of the castle of Montmayeur, while the hamlet of Léverogne keeps medieval traces blended with more recent structures.
