The first church built in this location dates back to the 8th century, commissioned by Patriarch Callisto. In 1348, a strong earthquake caused severe damage, although information about this event is scarce. Another earthquake on August 8, 1364, caused further damage. In the mid-15th century, the building was entrusted to Bartolomeo delle Cisterne to be rebuilt in Venetian Gothic style. The work took a long time; after the architect's death in 1480, the construction remained incomplete, and in 1502 a column collapsed, causing much of the church to fall. Shortly after, Pietro Lombardo was commissioned to rebuild it, creating the current cathedral in a style that combines Gothic, Venetian, and Renaissance elements. At the end of the 18th century, architects Giorgio Massari and Bernardino Maccaruzzi carried out a major internal renovation.

In June 1909, Pope Pius X elevated the cathedral to the rank of minor basilica.

The interior is divided into three naves: the central one with a barrel vault and the two lateral ones with a cross vault. Above the main portal, on the internal wall of the facade, is the Monumento equestre di Marcantonio di Manzano, a commander from Cividale who died heroically in 1617 during the siege of Gradisca. The sculpture, in lacquered wood, was commissioned in 1621 and created by Girolamo Paleario. Above the doors, there are four plaques that commemorate important moments in the history of the cathedral and the benefactors who supported it.

The cathedral houses works of great artistic and historical value, including:

•A wooden Crucifix from the 13th century, in the left nave.

•The altar of the Santissimo Sacramento, made in 1580 by Ercole and Orazio Liberale.

•The Pala di Pellegrino II, one of the medieval masterpieces of Italian goldsmithing, composed of 123 embossed gilded silver plates, depicting a Madonna with Child between the archangels Michael and Gabriel, and saints, with Patriarch Pellegrino II prominently represented. The style recalls Byzantine modules with Romanesque influences.

•A Vesperbild of the German school from the 15th century.

•A Madonna enthroned with saints by Matteo Ponzone (1617).

•The scene of the Stoning of Saint Stephen and the Last Supper, both by Jacopo Palma il Giovane (1606).

•The Annunciation by Pomponio Amalteo (1546).

•Frescoes in the sacristy by Giuseppe Diziani and Giuseppe Mattioni.

•The Via Crucis in terracotta by Max Piccini (1964).

Every year, on January 6th, the traditional Messa dello Spadone is held, a unique rite dating back to 1366.

In the right apse is the altar dedicated to San Donato. On the left wall, there is a large Annunciation by Pomponio Amalteo.