Gynaikokastro dominates between the Rivers Gallikosand Axios, just 35 km. away from Thessaloniki. The castle was founded by the Emperor Andronikos III Palaiologos. It was a powerful fortress. It is also known by Kantakouzinos’ dynastic struggles and civil wars of 1342.

In this castle, the Governor of Thessaloniki, Theodore Sinodinosthe FirstBuilderresorted in the summer of 1342, along with Kantakouzinos, his soldiers and a thousand noble people when they were endangered by an uprising. During 1350 Andronikos III Palaiologos visits AvretHissarand after 1350 Gynaikokastrowas held by the Emperor of Serbs, Stephen Dushan.

According to the tradition, the Avret-Hissarwas surrendered by Maroulia (wife of the Commander) toEvrenos, after several months of siege and resistance. This is the reason why it was named Gynaikokastro (Avret-Hissar); because it was so powerful that even a woman could defend it.

The fort stands on a hill, 201m high, with an area of ​​25 acres and it is surrounded by stone walls. The total length of the walls reaches 1601m. The gates of the castle are situated on the south side and on the northeast side. The Defense tower is located at an altitude of 201m,has an area of ​​126 sq.m and consists of a basement and ground floor. In the western part of the fortress and inside the walls, there is a well. Pre-Christian graves were also foundwith directionto the south, confirming the existence of settlements in the last three thousand years.

An important archaeological site for the prefecture of Kilkis is the one uncovered in Palatiano, a small village north of Kilkis. Remains of a large Macedonian city of the Hellenistic and Roman periods were found in the region. The city might be identified with the ancient Ioron.Excavations at Palatiano began in 1961 and so far have brought to light four impressive statues that are on display in the Archaeological Museum of Kilkis, while copies exist in the area that they were discovered. Ruins of buildings, chapels, and the cemetery of the city were found there. The area of Palatiano can only be visited after consultation with the Archaeological Service.