The Cathedral of San Rufino, built in the Romanesque style in the 13th century, already shows spectacular elements of this style on its façade. Carved arches decorate the doors, with a large rose window in the center and two smaller ones on the sides, allowing light to enter the church.

The interior was renovated in the 16th century and houses the baptismal fonts where Saint Francis and Saint Clare were baptized. The side chapels and ceiling are adorned with paintings depicting the lives of Jesus, Saint Francis, and Saint Rufino. Saint Rufino was a 3rd-century martyr who became the first bishop of Assisi, where he also died.

Beneath the cathedral square is the church museum, containing a collection of around 300 works, of which 100 are on display to the public.