The name of this village is a distance. Along the via Iulia Augusta, where Terzo stands today, there was once a milestone marking three Roman miles from Aquileia: hence the Latin name of the place, Ad Tertium, and hence the name it bears now. The milestone, indeed, is on the comune's arms. Two great Roman roads passed here, the via Annia and the via Postumia, both making for Aquileia, and the village already existed then. Even the boundaries are made of water running towards the same city: the river Terzo, with the canals Anfora and Morona, divides the comune from Aquileia, the Ausa divides it from Torviscosa, and the lagoon from Grado.
In 1800 the rich Vianello family, owners of the palace that is today the town hall, set up a citizen self-government of their own. That palace, deeply transformed in the eighteenth century, remains the most notable building, together with the church of San Biagio, neoclassical, built in 1843 and consecrated on 8 November 1846, which keeps in its apse a Trinity with choirs of angels painted by Sebastiano Santi; and together with the church of San Martino, in the hamlet of the same name, smaller but with more history behind it. Along the via Iulia Augusta, in a public park, stand the monumental totems of Luciano Ceschia. Friulian is spoken here, in its Gorizian variety, and the land is wine country: the territory is part of the Strada del vino di Aquileia. The village feast, though, is the pumpkin festival, held at San Martino on the Saturday and Sunday of the third week of October.