The fortified village of Isola was built between the thirteenth and the fourteenth century and is now visible from the outside. It was a fief of the Gentili Counts from Rovellone; in 1305 it was sold to the Municipality of San Severino Marche for 8,000 crowns. It retains parts of the medieval plan, such as the walls and the surrounding buildings. The main tower in large sandstone blocks is almost intact (m. 25). Next to the tower are some old buildings with arched doorways and windows. Within the walls is the parish church dedicated to St. George the Martyr, whose main entrance is unusually located under a large arch. The church houses precious frescoes made by Sebastiano Ghezzi in 1604.