Its name is related to its founder’s name Cassandros.
Ancient Potidaia was founded as a colony of the Corinthians in 600 BC. It used to be a financially rising commercial city with its own currency. In 479 BC it is being sieged for three months by the general Xerxis Artavazos but with no outcome. After the end of the Persian wars Potidaia becomes a member of the Athenian Alliance. In 432 BC, however, it is detached and that event was one of the triggers for the Peloponnesian War. After long-term sieging from the Athenians, the city is forced to sign a treaty and, according to the terms which were signed, Potidaia was forced to move its residents to Olynthos and Athenian citizens who had gained allotment to reside in the area. After the defeat of the Athenians in the Aigos Potamoi in 404 BC, Potidaia is included in the control area of Sparta and in 356 BC it is taken over and destroyed by Filippos B’.
In the place of Potidaia in 315 BC Cassandros decides to found Cassandreia along with the Potidaia settlement, the surrounding smaller villages and Olynthos. The new city is developed into a flourishing center which was often under contention.
During the Roman period, Cassandreia is referred to in the sources as one of the most important cities of the area along with Thessaloniki, while it keeps having its own mint. Around 44 BC it is turned into a Roman colony and welcomes the first roman colonists. Its second colonization occurs by Augustus around 30 BC. Since then, on its coins one can see the inscription COLONIA IULIA AUGUSTA CASSANDRENSIS.
Our knowledge on the first Christian centuries is limited. The 3rd century AD, the city is sieged without result by the Huns who manage, however, to destroy it in 540 AD. A few years later, the emperor Justinian I’ undertook its reconstruction. According to Papaggelos, the small settlement of Cassandreia after 1047 must have been abandoned, while in 1307 it was taken over by the Catalans.
Around 1407, Ioannis Z’ Palaiologos, despot of Thessaloniki at the time, fixed the wall and the canal on the isthmus of Cassandreia. He alsosecured the installation of constant guard because of the Ottoman threat in the area.
In the beginning of the 15th century, the Venetians ruled the peninsula of Cassandreia, they reinforced its fortification and installed garrison which remained in the city until the end of the conquest of the peninsula by the Turks in 1429-30.
During the Ottoman Occupation due to the new politico-economic conditions in the area, the strategic importance of Cassandreia was reduced and the city was devastated.
In 1793 the French Lansul Cousinery marks that at his times, Cassandreia was a poor village with thirty or forty families the most.
In 1924 the area is resided by refugees from Eastern Thrace who founded a new village named Nea Potidaia.
During excavations parts of an intermediate wall came to light, a wall which divided the peninsula from the rest of the land, connecting the two gulfs. This construction seems to have existed since the ancient times, however after the destruction of Cassandreia by the Huns in 539/40, Justinian I reinforced it significantly and gave it the shape that the ruins show today.
This wall is in its total about 1200 meters long and every 50 to 60 meters it is reinforced with square towers. Throughout the length of this wall eighteen towers were traced. For its construction it was used ancient material in second use (spolia) and it is clear that it went under different building phases.
In the middle of the isthmus, ruins of an arched gated are being saved, whose position indicates that it was probably the main entrance.
During excavations, among other movable findings, there is selected glazed pottery dated to the second half of the 14th century AD, as well as several coins which cover the period from the 3rd century to the 16th century AD.
Ancient Potidaia, being a sea-front city, had a harbor which served the commercial relations of the city to the south of Greece and mainly Corinthos. Since the city was built on an isthmus, it probably had two harbors, one on the Thermaikos Gulf and one the Toronaios Gulf. Part of a stone wall which crosses the canal with a North-East direction and which is characterized by researchers as part of the ancient pier, could be part of the harbor installation.
Later, the port of Cassandreia is also turned into an important commercial crossroad, while in the sources it is referred to as a place which had very good shipyards. The location of the Hellenistic port is not entirely known, because of the deformation of the area’s topography which changed with the re-opening of the canal in the beginning of the 20thcentury (its primary re-opening was due to Cassandros at the time of the foundation of Cassandreia.).
Cassandreia as well as its predecessor Potidaia, according to written sources, were fortified at their perimeter all the way to the sea. The continuous and sometimes long-term sieges of the city through the centuries, signify the strength of their walls.
The existence of a south wall in Potidaia is also confirmed by Thucidides who mentions that its demolition was one of the terms the Athenians put to the defector citizens of the city.
On the West side of the isthmus, south of the wall, an enclosure was added – a four-sided shaped fortress – which is attributed to the Despot of Thessaloniki Ioannis Z’ Palaiologos. According to the chrysovoulon of 1407, the Despot made great reconstructions to the intermediate wall and opened the canal for better fortification of the area.
This canal seems to be opened during the time of the foundation of Cassandreia but it went under filling in time. After a while the canal closed and was dug again during the Greek Revolution in 1821.
In 1424, the Venetians tried to make new repairs to the fortification, but it seems that they were never completed.
In the times of the Ottoman domination the fortification of Cassandreia was abandoned.
Remains of the fortification of the city are being preserved and are visible.