Vasto is a little city by the sea at opposite side of Rome and comune on the Adriatic coast of the Province of Chieti in southern Abruzzo, Italy. It was also called in the Middle Ages as Guastaymonis or Vasto d'Aimone and also Waste d'Aimone. Renamed Istonio under the Fascist Rule, it took the current name of Vasto in 1944.

Main sights include:

• Vasto Cathedral (Cattedrale di San Giuseppe)
• Church of Santa Maria Maggiore [it], the largest and oldest (mentioned in a document as early as 1195) church in the town, with a quite tall bell tower. Damaged by the Turks in 1566, and by a fire in 1645, it received a thorough restructuring in 1735 in which it got the current shape. It hosts one of alleged Jesus' crown of thorns (Sacra Spina).
• Castello Caldoresco
• D'Avalos Palace (Palazzo D'Avalos) and the Musei Civici
• Below the hill on which the town is located, the beach resort town of Marina di Vasto offers a large sandy beach and several hotels and other facilities.
• Further north the coast becomes rocky and features interesting pebble and stone beaches and coves, as well as the typical trabocchi, typical wooden fishing machines of the Southern Abruzzo coast. Amongst the natural areas, also featuring a number of sandy and rocky beaches, is the protected natural area of the Riserva Naturale di Punta Aderci, whose beaches were voted in 2014 third of the top 20 beaches in Italy.