Archaeologists unearthed a "unique" Minoan monument atop a hill on the island of Crete overlooking the newly planned airport, the Greek Culture Ministry said.
The ministry in a statement said the building had been found on a hill at Kasteli, nearly 500 meters (1640 feet) high, that was previously earmarked for the new airport radar.
"It is a unique discovery of particular interest," Culture Minister Lina Mendoni said, with the ministry statement adding that it is the "first of its kind" found on Crete.
The circular stone building, about 1,800 square meters (19,300 square feet) in size, contains eight "nearly labyrinthine" rings connected via small openings, it said.
The intended use of the complex is still unknown, and may have served a ritual purpose, but saw its main activity between 3,700 and 4,000 years ago, the ministry said.
A large quantity of animal bones was found on the site.
The discovery means that the planned radar will have to be relocated, Mendoni said.
The new airport, designed to accommodate 10 million travelers annually, is to be delivered in 2027.
The Minoan civilization, a naval superpower of the Bronze Age era, flourished on Crete and other Aegean islands until about 1500 B.C.
