Between 1981 and 1996 E. Di Filippo Balestrazza, from the University of Padova, conducted numerous excavation campaigns in the north-west quarter of the ancient colony of Iulia Concordia, today Concordia Sagittaria. These excavations aimed to bring to light the remains of the Roman theatre. The position of the semicircular monument was proposed, on the evidence of the “stone quarriers” of Concordia at the end of the 1800s, by Dario Bertolini, Honorary Inspector for excavations and a correspondent of the “Notizie degli Scavi di Antichità”, following the discovery of the cemetery of the Militi at Concordia, as being in the north-west sector of the colony, as shown on the plan draw in 1880 and published in “Notizie Scavi” of the same year. A first drawing of the building had been made by Stringhetta, the head workman, from which Bertolini made his plan. The most important results came from the central area where the remains of the theatre building were uncovered. Various parts of it were excavated. Part of the cavea, although completely robbed, revealed in negative the robber trenches of the radial walls which supported it. The orchestra was the best preserved part of the theatre: part of the brick paving of the crown was found. Lastly the proscenium was investigated, of which the wooden floor boards, completely burnt, were identified and which belonged to the original flooring. Some of the architectural elements which probably decorated the façade were also recovered. During the last years the backstage area has been investigated, revealing the existence of a large building abutting the stage itself, limited to the east by a stretch of road originally paved in trachyte basoli. The areas opened in the vicinity of the theatre are of interest: Trench 1 revealed traces of occupation continuity during the ruination of the building; Trench 3, the northernmost, was situated along the line of the city walls not far from the theatre. The finds attest a long occupation of the area, from prehistory to the late antique period, when the theatre was abandoned and robbed. The monument’s use can be dated to between the beginning of the 1st century A.D. and the 4th-5th centuries A.D.