Gla’s enormous Mycenaean fortress in Boiotia (more than 10 times the size of the contemporary Mycenaean fortress of Tiryns, and nevertheless not mentioned in the Iliad of Homer) was located near Lake Kopaïs, which was largely drained during the Mycenaean period. For this goal, the water of the Kephisos and the Melas was drained through an ingenious system of channels and dams, leaving an enormously fertile area available for agriculture. This area, according to mythology, came under the control of Orchomenos in Boiotia, which must have owed much of its legendary wealth to it. The current name Gla comes from an Albanian word meaning “fortress”, while the local residents speak of Paliókastro, “old castle”. The antique name of the complex is unknown.

The fort was almost certainly part of the protection of this important hydraulic engineering work. The fortress was completely surrounded by a huge 3 meters thick and 2.8 km. long Cyclopean wall, with no less than 4 entrances, accessible via artificial ramps, on top of a natural elevation, so that the whole will have been virtually impregnable. Central to the fort were the rooms for the managment of the area, mainly of an administrative nature. It is striking, but explainable, that Gla does not have a real megaron structure, as was the case in many other large Mycenaean centers, nor a bath building. It will therefore not have been an independent palace kingdom. The administrative spaces consist of two large wings, connected by long, sometimes double corridors. To the south of the official spaces were two elongated spaces with an unknown function, possibly storage spaces, while the entire managment complex was situated in a spacious courtyard, accessible from a monumental entrance gate.

For the drainage of the lake served  two  long channels at about 1 km. located north of Gla with a total of almost 50 km. At the end of the Mycenaean period, the maintenance of the drainage system fell into disrepair, so that from classical antiquity there was again a lake, which was  drained for the second time in the 19th century.

Pictures above, the Kopaïsmeer now, with (circled) the fort of Gla, close-up of the fort; below, details of the walls and the offices.