Gynaikokastro Castle is trapezoidal and covers an area of approximately 25 acres. The outer curtilage is 614m. long, founded directly on the bedrock and reinforced by long intervals with rectangular and semicircular towers. The masonry consists of rubble with occasional brick and strong mortar as binder. Many parts of the enclosure have been damaged by erosion, while in almost all the southwestern part, at the bearing point, theres is lack of masonry (depth 30cm. up to 1.00m.). Parts of the ramparts are preserved at the eastern precinct and at the acropolis.
Two gates provided entrance to the castle; the main gate in the southeast side in which led a paved likely vehicular road and the secondary gate located near the inaccessible northeast corner of the enclosure, close to the acropolis, accessed by carved rock steep stairs, ensuring autonomy. The main gate, now almost destroyed, was reinforced by triangular overhang on the south side and was protected by two partly preserved bastions, which protrude from the wall, having no functional dependence with it. The ramparts, indispensable for defense cannons, are an evolved form of fortification, which was introduced in late Byzantine years.
The acropolis, in the northeastern part of the castle, has a separate fortification quadrilateral shape. The south wall is can today be seen at a length of 11m. and a height of approximately 13m.; the west wall is partly preserved (39m. long and 3-8m. high). Access to the ramparts provided partly preserved carved stairs, while the fronts of the arches are constructed with the technique of hidden plinth in incomplete form, a custom method used in castles of the late Byzantine period. At the top of the acropolis Andronikos raised a strong tower 13.46m. by 9.40m. preserved today at a maximum height of 7.50m. Masonry consists of irregular stones and brickwork of four to five block series, at irregular intervals. The tower, originally of two floors, is divided into two connected main areas, the west and the east room. Entrance to the tower probably provided a wooden staircase. On the ground floor two vaulted cisterns are preserved. The cisterns are dug into the rock and separated by a 1.6m thick wall. The eastern cistern's dimensions are 4.8m.by 4m. and 5.04m. high; the west is 4.8m. By 3.2m. and 4.9m. high. Their inner walls are coated with double hydraulic mortar layer, which is preserved in good condition. The two cisterns are connected by a narrow passageway 50cm. from the bottom. Ventilation and lighting is provided by a series of openings in the exterior walls.
The two rooms are separated by an internal wall 0,96 – 1,06m. thick, which is partley preserved. During the excavations fallen layer of frescoes came to light, including a fragment of the monogram of Palaeologos, indicating the existence of a chapel. Regarding the internal structure: a) On the plateau of the hill, south of the tower, the foundations of a rectangular building width 7.25m. and 11.50m long were revealed, possibly related to the billeting of permanent garrison. b) Ιnside the castle successive layers of masonry represent different phases of construction; a roughly constructed stone-built pipeline has also been revealed, of likely post-Byzantine times. A column, 2.28m long reveals the position of the castle church. The existence of chapels within the towers was common in Byzantium and served the religious needs of the garrison. c) Inside the eastern precinct relics of post Byzantine walls were discovered, delimiting the existence of buildings of unspecified use. d) In the northeastern part of the acropolis mud-made walls of the late post-Byzantine period were revealed, probably stable facilities. e) New building evidence on how the castle foundation and earlier building remains below the foundation level confirm that this position was used before building PalaiologIan fortification project.
There are however, some special components and details, the observation of which may draw interesting conclusions about the evolution of fortress architecture in Greece and generally Byzantine world. Specifically:
a) The application of random masonry system with zones with multiple brick lines found in the Gynaikokastro acropolis tower, is a widespread technique, common in the fortifications of the Late Roman period (Maximianoupolis, Anastasioupolis, Komotini, Maronia, Didymoticho, Filippi, Drama). It occurs mainly in fortifications associated with important founders, like the fortifications of the Kosmosotira Monastery, the Christoupoli acropolis tower, Anaktoroupoli, Chrysoupoli and in Thessaloniki or in large projects, as in Didymoticho, the five-sided tower Serres acropolis and fortress of Pythian.
b) The domed covered ceilings of the tower floors are not common in the Late Byzantine period, during which separation dominates either only with wooden floors, or a combination of wooden floors and vaulted coverage.
An also rare component of the late Byzantine years, is housing all floors of the tower with domed cover art, found not only in the tower of Gynaikokastro, but also at the great tower of Pythian, at the castle of Zihni, at the tower of Orestis in Serres acropolis and at the acropolis of Polystylo, John Kantakouzinos work.
d) The formation of the inner side of the wall with large arches is one of the most famous fortification practices found by the late Roman until the late Byzantine period. With this method less raw material is used, there's improved static design of the wall, the needs of the garrison are best served and it is easier to repair cracks of the wall. The technique of hidden block, known in Byzantine architecture since the 10th century was mainly applied in the middle Byzantine period, but disappeared during the late Byzantine period.
The technique used in Gynaikokastro, applied to a limited extent in fortress architecture in Mid-Byzantine period and was particularly used in church and fortress architecture in the late Byzantine period and especially in Palaiologian period. A similar example is the castle of Komotini and the fortress of Pythian.
Source: Athena Tokmakidis - Archaeologist: "THE CASTLE OF GYNAIKOKASTRO IN KILKIS STUDY – POROPOSAL FOR RESTORATION AND PROMOTION "