Built on the site of the ancient city of Potidaea, 33 kilometers south-west of Polygyros, it was re-founded in 1922 by Greek refugees from Platanos in Eastern Thrace and Kalolimnos (now called Imrali) which remained under Turkish rule.

In 431 BC, after the siege by the Athenian general Kallias (in which Socrates fought bravely as Alcibiades recounts at the end of Plato's 'The Symposium'), it was subjugated and subsequently forced to take in settlers from Athens.

After a period of desertion of about 40 years, in 316 BC, Kassandros built a new city on the site of Potidea, which was named after him, Kassandria (this may indicate that he intended to make it his capital, or at least an important naval base).

Its castle, being of great importance for the security of the whole peninsula, was repaired by John VII Paleologos in 1407 and later by the Venetians when they were given the city of Thessalonica in 1423 in an attempt to keep it from the Ottomans.

They fought hard until the ”turmoil of Kassandra“, the well-known "holocaust", when the canal 'ran with blood', which is commemorated with official celebrations every year on its anniversary, November 14.