Archaeologists excavating a vast 3,300-year-old fortress northwest of Athens are hoping to shed light on one of the most impressive engineering feats of ancient Greece.

The Culture Ministry says the results of work at Glas, a low, flat hill commanding a sprawling plain, have been “particularly encouraging,” revealing meticulously planned building complexes of an uncanny uniformity unknown in other contemporary sites.

For most of its history the plain was a lake surrounded by swamps. It was only fully drained in 1931. But for a brief period in the 13th century BC, local rulers changed the river courses and built huge dikes to create thousands of acres of farmland.

Just decades later, Glas and its waterworks were abandoned, while the surrounding fields reverted to wetlands for the next three millennia. [AP]