Vasto (Abruzzese: lù Uàštë; Ancient Greek: Ἱστόνιον, romanized: Histonion, Latin: Histonium) is a comune on the Adriatic coast of the Province of Chieti, in southern Abruzzo, Italy.

Ancient geographers cited the town as located in the territory of the Frentani and apparently under Julius Caesar[4] did not obtain the rank of a colonia, but continued to bear the title of a municipium, as we learn from some inscriptions.

[6] Among the numerous inscriptions which have been found, one of the most curious records the fact of a young boy named Lucius Valerius Pudens having at thirteen years of age won the prize for Latin poetry in the contest held at Rome in the temple of Jupiter Capitolinus.

[7] The name of Histonium is still found in the Itineraries of the fourth century[8] and it probably never ceased to exist on its present site, though ravaged successively by the Goths, the Lombards, the Franks, and the Arabs.

[9] After the collapse of the Western Roman Empire, the region was occupied by Germanic tribes until Justinian's Byzantine re-conquest, which included the province of Samnium, of which Histonium was a key town.

Only superficially shaken by revolutionary events in 1799 (a short-lived Republic of Vasto was immediately overthrown by the sanfedista, or loyalists), the city's history was reflected in the nation's throughout the Restoration to the Unity of Italy when a liberal elite governed.

Despite a devastating landslide (1956) that dragged a significant part of the eastern ridge – now Via Adriatica – into the gorge below, the years following World War II witnessed industrial, urban, and socio-cultural development.

The city also discovered its tourist vocation: besides the progressive development of its beaches in Marina di Vasto, Roman-era thermal baths, mosaics, cisterns and remains of an amphitheatre were found and restored.