The emergence of Grado was told us by Paul the Deacon (720-799 AD), who, after saying that “non longe ab Aquileia Gradus Insula est” (“The island of Grado is located not far from Aquileia”), continues: “[.. .] Paulus (Episcopus) Langobardorum barbariem metuens ex Aquileia ad Gradum Insulam confugit secumque omnem suæ Thesaurum ecclesiae deportavit [...]” (or, “Bishop Paul, fearing the wrath of Longobards, escaped from Aquileia to the island of Grado, carrying the treasure of his church”) [See, G. Bovini, “Grado Paleocristiana” [“Early Christian Grado”], Patron, 1973: 2, 8]. Grado, therefore, came from a “rib” of Aquileia, the inhabitants of which, terrified by the invasions of barbarians, sought refuge in the Venetian lagoons; after all, the birth of Grado is absolutely similar to that of Venice.

Grado is in fact a small island in the Adriatic Sea, about four leagues to the South of Aquileia. It seems that in Roman times it was a big "Vicus" or township, called “Gradus” for marble steps built for the convenience of those who climbed and descended from ships; in fact, according to etymology, which today enjoys considerable credibility, the city's name derives from the Latin word “gradus”, meaning "step"; the meaning we give to the term "step" has been convincingly explained by L. Bosio, who writes that the name of Grado derives from  "[....] 'gradus', which, as say precisely Uggeri (1968, p. 235) ‘indicates the mouth, the transition between two different waters, as from the sea to a river or a lagoon”, and more specifically a port call at the mouth of a river or entrance to a lagoon [...]" (See L. Bosio, “Le strade Romane della Venetia e dell'Istria” ["The Roman roads of Venetia and Istria"] , Programma, 1991: 249).

Therefore, the etymology of "Gradus" should be interpreted as a "port city". In fact, Grado was born as part of the extreme port system of Aquileia, as a first port of call for ships, which, from the Adriatic, to arrive at Aquileia, had to go up the river “Natisone”. Anyway, the contemporary studies confirm the hypothesis of "Gradus" as "port city", because, as we read in “Grado nella Storia e nell'Arte” ["Grado in History and Art] (Arti Grafiche Friulane, 1980: 525) [.. .] As regards the etymology (especially after the explanations of H. and R. Kahane (‘The toponymy gradus’ in ‘Names’, 1960: 240-243) and L. Michel ( ‘Toponymie Languedocienne: le term ‘Grau’’ in ‘Revue Internationale d'Onomastique’, XV, 1963: 81-88) there are no doubts: it derives from the Latin common noun 'Gradus',  meaning  ‘port’ [...]".

The town of Grado is therefore of Roman origin; "Gradus", in fact, was the first port of call of the vessels coming up the river "Natissa" to Aquileia, the most important city of the East Roman Empire and seat of the "X Italian  Region of ‘Venetia’and Istria.” At first it was a “Castrum”, with a city wall of rectangular shape that corresponds to today's Old Town; then, it became, because of the barbarian invasions, the permanent residence for populations from hinterland, seeking refuge from Attila (452). In 568, before the Lombard invasion, the Archbishop of Aquileia, as Paul the Deacon tells,  transferred the Bishop's see, setting up as "Venetiarum et Histriae Patriarch" ("Patriarch of 'Venetia' and Istria '), but the Patriarchate was always at Aquileia. Patriarch Elias (VI century) completed the construction of the Cathedral and embellished the little village with houses of worship, and reinforcing the importance of the patriarchal chair of Grado, who was pro-papal, but coming into conflict with Aquileia, supported by the Lombard dukes.

The disagreements between the two cities were accentuated by the proclamation of the Patriarchate of Grado. The city was, therefore, the religious capital of an area that went from Istria to Chioggia, and it had a great commercial and artistic economic development; besides, until 1451 it was Metropolitan capital of all the churches in coastal cities, including Venice, on which Grado exerted  a constant and long influence. But with the abolition of the Patriarchate (XV century) and the greater power of Venice, Grado lost its importance, and the only economic activity was concentrated in fisheries. After “Campoformido” Treaty of 1797, Grado passed to Austria and, except for a short domain of the French, in 1918 returned to Italy. During the nineteenth century, the city began its economic revival, thanks to its tourist function. In 1892 it became the official station care of Habsburg Empire. Grado, called also the “Sun Island” for its beaches,  in the twentieth century strengthened its importance as a tourist centre of excellence.