What to see
The exterior features a Romanesque-Gothic facade preceded by a portico added by Patriarch Maxentius in the ninth century. This connects to the remains of the fifth-century baptistery via the so-called Church of the Pagans. Towering over the Friulian countryside is the 70-meter campanile, built in 1031 by Patriarch Poppo. Constructed using massive marble blocks from the ancient Roman amphitheater, its design was reportedly inspired by the Lighthouse of Alexandria. Inside, the space is divided into a nave and two aisles by twenty-eight columns. Following a 1348 earthquake, Patriarch Marquard of Randeck introduced the pointed arches in the central nave, while Venetian carpenters crafted the impressive wooden ship-keel ceiling in 1526. The vast mosaic pavement unfolds across four main bays. The first displays Solomon's knots and a depiction of a rooster fighting a tortoise, symbolizing the struggle between good and evil. The second bay features medallion portraits—believed by some scholars to represent Emperor Constantine, his mother Helena, and his four sons—alongside a depiction of Jesus as the Good Shepherd, styled similarly to the pagan god Mercury with a sheep across his shoulders. The third bay, which once held the altar, presents a winged Victory with a palm and crown, an allegory for the triumph of the Christian faith. The final bay illustrates the biblical story of Jonah amidst a sea teeming with fish. In the left aisle stands the eleventh-century Holy Sepulchre, a replica of the Jerusalem shrine used in medieval Holy Week liturgies. Nearby, an exposed section of flooring reveals three distinct eras: the lowest level from an Augustan-era Roman villa, a middle cocciopesto layer, and an upper geometric pavement bearing black scorch marks from Attila's fire. The apse area contains eleventh-century frescoes, while the adjacent St. Peter's chapel preserves fourth-century decorations. Below the presbytery, the twelfth-century Crypt of the Frescoes, commissioned by Patriarch Ulrich of Treffen, illustrates the origins of Aquileian Christianity and the life of Saint Hermagoras, the city's first bishop. Behind the apse and bell tower lies the Cemetery of the Fallen. This solemn ground holds the graves of ten unnamed World War I soldiers, Saint Hermagoras, and Maria Bergamas, the woman who selected the body of Italy's Unknown Soldier.
Visiting
Exploring the basilica involves a descent through Aquileia's architectural stratigraphy. The remains of the original "Theodorian halls"—two parallel 37x20 meter spaces originally connected by a vestibule used for confirmations—can still be inspected beneath the current nave and the bell tower's foundations. While the northern hall (expanded to 73x31 meters by Bishop Fortunatianus) was completely lost to the Huns, the massive southern hall, expanded by Bishop Chromatius to 65x29 meters, provided the footprint for the medieval reconstruction that visitors walk through today.
Our editors' tip
Take a close look at the portrait medallions in the mosaic's second bay. Notice how the ancient artisans used lines of black tesserae to sharply define the facial features, creating a striking color contrast with the garments that makes the figures distinctly stand out.