The artefacts unearthed by archaeologists in the area next to the parish church in the 1960s and in 2012 are extremely eloquent. The digs have brought to light a marble-faced tomb that can be attributed to the three Cantia martyrs, killed in AD 304; they have also confirmed that a basilica commemorating them was built here very soon, as early as the fourth century. This was replaced two centuries later by a larger building that was decorated with a wonderful polychrome mosaic, as the surviving fragments attest. The research also revealed the existence of buildings predating the martyrs’s tomb: this had previously been the site of a luxurious early imperial-period Roman villa, perhaps belonging to the very same Cantia family, who are known to have been landowners in the area.
Some of the ancient artefacts that were found have been placed in the Antiquarium next to the parish church, which also contains finds from the place nearby where Protus, the three Cantia siblings’ tutor, was buried after being similarly martyred.
The objects displayed help trace the history of San Canzian d’Isonzo, first as an important Roman settlement, then from the fourth century AD as a centre of worship of the martyrs. The stunning mosaic fragments are especially striking. These come mainly from the floor decorated with polychrome geometric patterns in the later basilica built in memory of the Cantia martyrs.
Recently (summer 2023), following the preliminary verification procedure for the redevelopment work of the Ss Canziani Martiri square, excavations have brought to light the southern wall of the so-called early Christian basilica, its corresponding floor plans, and some mosaic fragments, thus confirming the presence of several structures succeeding the basilica. Additionally, during the expansion of the excavation area, a Paleoslavic necropolis was discovered, with burials dating back to the 9th and 10th centuries, containing the remains of 35 individuals.