Cassandrea, Cassandreia, or Cassandria (Ancient Greek: Κασσάνδρεια, Kassandreia), was once one of the most important cities in Ancient Macedonia founded by and named after Cassander in 316 BC located on the site of the earlier Ancient Greek city of Potidaea. The fact that Cassander named it after himself suggests that he may have intended it to be his capital, and if the canal which cuts the peninsula at this point was dug or at least planned in his time, he may have intended to develop his naval forces using it as a base with two harbours on the east and west sides. The territory also at one time comprised the areas of Olynthus and Mekyberna to the northeast, Bottiaea to the northwest and the small peninsula of Pallene (now Kassandra) to the east. At the end of the Roman Republic, a Roman colony was settled around 43 BC by the order of Brutus, by the proconsul Q. Hortensius Hortatus. The official colonial name was Colonia Iulia Augusta Cassandrensis. The colony enjoyed ius Italicum. It is mentioned in Pliny the Elder's encyclopaedia (IV, 36) and in inscriptions.
During the Byzantine period it was briefly important in the 1423–30 period, when the Venetians captured it from the Turks and used it as a naval base. They also captured the castle of Platamon on the western shore of the Thermaic Gulf, and so had complete control of the approaches by sea to Thessalonica, which they had taken over after it had been offered to them by the ruling Despot. Like Thessalonica, it fell to the Ottomans in 1430.
The modern settlement of Kassandreia (named Valta before 1955) lies to the south of the ancient site. The ancient site of Cassandreia (renamed Nea Potidaia) is not excavated.
- F. Papazoglou, Les villes de Macédoine à l'époque romaine, Supplément du BCH 16, Athens, 1988.
- D. Samsaris, La colonie romaine de Cassandréa en Macédoine. Colonia Iulia Augusta Cassandrensis (The Roman Colony of Cassandra in Macedonia. Colonia Iulia Augusta Cassandrensis). Dodona 16(1), 1987, 353-437.
- John R. Melville-Jones, 'L'ixola di Caxandria' in Thesaurismata 27, 1997, 125-138.