Julia Concordia, important Roman colony, was founded in 42 A.D. near the crossroad of "Via Annia" with Postumia Way; particularly flourishing in the first two centuries of the Empire, in late ancient times it became the seat of an arrow factory (sagittae, from which the name given to the town in the last century at the period of the first excavations) and bulwark, together with Aquileia, of the eastern border. Elected episcopal seat in 389, it continued to flourish until the arrival of the Longobards, with whom its definitive decadence started. It became a quarry for building materials in the most ancient times : the abundance of the architectural remains which were reused to build the Paleochristian church is proof.
The first regular excavations were carried out at the end of the last century bringing to light important monuments of the colony : the bridge and the theatre, are still visible today. The forum situated at the crossroads between angle and decumanus of the main streets, the presumed arrow factory. Other important remains are those situated in "Via dei Pozzi Romani " and a big graveyard on the left bank of the Lemene river, consisting of about 260 tombs of the late Ancient Age whose inscriptions, owing to the impossibility of keeping them on the site, were removed and taken to the National Concordia Museum of Portogruaro.
The most important remains are situated in Santo Stefano Cathedral square under and by the side of the church.Its a complex of monuments, brought to light from 1950 to 1970, that includes two pagan burial sites both with three niches. One of the most ancient Christian monuments of Veneto, a trichora stands in front of them.It is a building with three apses, originally built in the middle of the IV° century A.D. as a monumental tomb to honour the relics of martyrs.
Later, it became with the addition of an avant-corps made of a nave and two aisles, a small basilica with a front court and a burial area with engraved tombs and inscriptions at side. In 1168, the bishop Reginpoto built the Baptistery . It dominates the excavations and repeats faithfully the architectural structure of the ancient trichora. A large Basilica stands on the northen side of the trichora , part of which is used and its courtyard.
The church was used until the second half of the VI° century A.D., with different modifications in particular in the presbyterian area and the floor. It was destroyed by fire and its ruins were covered by two metres of alluvional sand.
A smaller three-apse church was built two centuries later which closed the eastern boundary.
The ruins of the foundations of two aspes sunk in the allovional soil are now visible.
At the end of X° century this late medieval church was replaced by a Cathedral transformed, in its structure, in 1466 and is still used today.
In recent years the excavations have been taken up again in the square in front of the church and the Early-Christian complex.
These excavations have brought to light a fine stretch of a Roman way with trachyte paving stones which still bear the traces of cart-wheels.
The street which linked Concordia to the Annia way came out of the eastern Town Gate.
To the south the ruins of the Roman storehouses stand.
This consists of different and parallel buildings divided into paved rooms, first in wood and then in brick. In a ditch which ran along the south-west side of the storehouses the big sewer was drained.
It was originally covered by a vault, which left the city passing under its walls.