After the Byzantine domination, from the 11th century Trelizzi was under the influence of the counts of Giovinazzo, whose member Amico fortified both the cities.

It had a castle which at one time was very strong, and occasionally resorted to by the Emperor Frederick II, and later by the Aragonese sovereigns of Naples.

[3] Its remains include a 31-metre (102 ft) high clock tower in the center of town that was built by the Norman conquerors in the 12th century AD.

[3] In 1745, a fine Greek-made inkstand inlaid in silver was found in a nearby, ancient cove, in Suberito (at now, Sovereto).

In the centre of the city is notable the big Palace built by the Barons de Gemmis, with the annexed church of Santa Maria La Nova.