The powerful Acropolis, in the towers of which still lives the Byzantine spirit, stands epically on the imposing pine-hill which dominates the modern city of Serres.

     The Byzantine Acropolis was built on the site of an ancient fort which defended the city in the 7th and 6th centuries BC in the Byzantine period, it is referred to in many golden bulls (imperial decrees) of various Byzantine emperors as the “Castle”. With time, the wordcastle ended to mean the whole city. Unit the beginning of our century, the inhabitants, of Serres were Known by the neighboring villages as the “Kastrinoi” (inhabitants of the castle). After the Franks conquest, the Acropolis was known as the “Castelli” a name that it preserved until the Tourkokratia (Turkish Dominion). The Turks gave it the name of “Bas Koule” (=top tower), probably after the large tower of the west wing. Its current name “Koulas” (tower) originates from the Turkish one. In Byzantine times, the Acropolis was enclosed by a spindle shape strong wall, extending from West to East. It encloses various Byzantine buildings, i.e. the houses of the administrators and other officers of the State. The Acropolis also housed the appointed by the Byzantine authorities, commander known as the “guardian of the castle”.

     Leon Ajanetes was a well known guardian of the castle and he endorses golden bulls of the first half of the 14th century. According to the traveler Evliya Celebi, the Acropolis wall had two gates, one to its east and one to its west end, very close to the respective towers. Traces of the second gate can still be seen today near the large tower of the west side. Tall and strong towers reinforced the defense of the wall, out of which only the strong and stately tower of the west side “The Tower of the King” still stands only destroyed at the top. This huge tower of presumably almost 20 meters had a double mission: it protected the city on one part and on the other part, it constituted the last defense post in the case where the enemy captured the remaining parts of the Acropolis. An interesting inscription on the right end of the “Tower of the King” reads, to the prevailing opinions: “ΠΥΡΓΟΣ ΑΝΔΡΟΝΙΚΟΥ ΒΑΣΙΛΕΩΣ ΟΝ ΕΚΤΙΣΕΝ ΟΡΕΣΤΗΣ” (=The Tower of Andronikos built by Orestes). 

     The foundation of the Byzantine Acropolis dates from the 9th century AD. It is then that for the first time, historical sources mention that Emperor Nicephoros Phocas reinforced the city of Serres. The irresistible Acropolis had a better fate than the wall of the city. It manages to survive the terrible barbarian ravages and destruction. Even in 1204 AD when the walls of the city completely collapsed, the Acropolis escaped the catastrophe. Nevertheless, the definitive capture of Serres by the Turks, in 1383 AD brings along the desertion and progressive demolition of the Acropolis as the Turks were systematically destroying the castles, so that they do not become breeding grounds of the resistance, in the event of a revolutionary movement of the unredeemed Greeks.