Our town's origins date back to the third century b.C., when the Romans founded a new colony called Castrum Novum, which became an important road junction and commercial harbour.In the Middle Ages the town was renamed Castel San Flaviano, in honour of the Patriarch of Costantinopile, whose relics, according to a legend, miraculously reached Giulianova's coasts.

The medieval town became property of the Acquavivas, who made of the town their residence until its destruction, occurred in 1460 during the battle of Tordino fought between Federico Montefeltro and Alessandro Sforza's troups and Jacopo Piccinino and Bosio Santafiore's ones.
About ten years later the Duke Giuliantonio Acquaviva, instead of rebuilding san Flaviano, founded a new town which was named Giulia. 
Giulianova's peculiar planning remained unchanged until the second half of the 19th century, when a demographic and economic increase led the inhabitants to move outside the walls and to settle along the shore (even thanks to the railway built in 1863).

The Duke of Atri and Teramo, Earl of Conversano and San Flaviano, after regaining San Flaviano left it because the place, once healthy, was now covered by stinking marshes which caused fevers and deathly deseases: the lands were not reclaimed because of the shortage of the period, the inhabitants died or left the town.

The battle fought in 1460 and Matteo de Capua's sack reduced San Flaviano to a heap of ruins. Instead of rebuilding the town, ravaged by the fury of men and by the natural forces, Giulio preferred to build a new town on a higher place not far from the ancient walls, and he called it Giulianova in honour of his own name.
Here it was the new town, over a charming hill dominating the Adriatic Sea, with a fertile ground rich in everything that one could wish for, under a bright and clear sky and near the sea, with a wide horizon delimited by the azure waves of the Adriatic and by the superb chain of the Appennini, with the towering Gran Sasso, and irrigated by two rivers, Tordino and Salino. The town had the shape of a quadrilateral, surrounded by strong scallop-adging walls with loop-holes, and it stood on top of a hill which slightly slopes down. The place was protected by seven towers, which remained standing until1860 and of which it is still possible to admire one, almost intact, with the original Acquaviva's coat of arms; the tower had three main doors, and a beautiful castle or fortress; embellished by a large square, whose floor was made of bricks put in dutch bond, the square had a sumptuous palace on one side (where the Earl lived), and the splendid temple dedicated to San Flaviano on the other one. Since its foundation, Giulianova remained always property of the Acquavivas Dukes of Atri.
The last Earl of San Flaviano and Duke of Atri was Luigi, general in the National Guard and senator of the Reign. But having nobody of his four sons a male heir, and since Francesco, married to the noble Donna Maria Zunica of Castellina, had an only-child, Donna Giulia, all the Acquaviva d'Aragona's titles were inherited by this woman. In the meanwhile the inhabitants of Giulianova, after the destruction of the ancient town and their moving to the new one, chose the image of Giuliantonio on horseback as their town coat of arms.
In 1749, the Aragona Real coat of arms was added to the original one.