Opi features many places of interest including the 17th-century Town Hall, the baroque chapel of S. Giovanni Battista and the church of S. Maria Assunta with its 12th-century towering belfry.

The church, repeatedly destroyed by earthquakes, was entirely rebuilt in the 17th century and holds three anonymous 19th-century oil paintings depicting the Baptism of Christ, the Beheading of John the Baptist and the Purgatory.