The tower (donjon), which overlooks the highway, is an imposing medieval fortress.
Important discoveries are the board of Hellenistic wall, that confirm the suggestion that on this position was the ancient Greek city Herakleion and the gate in the wall of the donjon. The core of the city Herakleion remains to be found, but it is posited that it is located on the northwest side of the castle's hill due to shells and coins found during recent excavations.
The place, which today is occupied by the castle, was used by the city of Herakleion (Ηράκλειον) in pre-Christian times. Not only on the top of the castle hill, but also at the foot of the hill, were settlements that were assigned to this ancient city. Around 360 BC Skylax of Karyandar described the place as "the first Macedonian city behind the river Pinios". The Roman historian Titius Livius has a more accurate position determination. "Between Dion and Tembi lying on a rock," he described the place, which is identical with the position of the castle. But even earlier, since the Bronze Age, a settlement of the castle hill has been proved.
In the year 430 BC, The Athenians conquered the place to control from here the Thermaean Gulf to their possessions on the Chalkidiki. At the same time, the country's most popular north-south route runs along the hill. At the beginning of the 3rd century BC, the city and the now established port were destroyed. By what, or by whom, is not exactly known.
By User: Bgabel, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22678419