Excavation work next to the uninhabited Greek islet of Keros, already identified as the enigmatic hub of a forgotten religion, has now revealed traces of intense industrial activity more than 4,500 years ago, Greece's Culture Ministry announced on Wednesday. The work, which took place last summer showed that Dhaskalio, a rocky islet once joined to Keros, was once almost completely covered in unique monumental structures of gleaming white marble. It also had metal-working facilities and houses, with a sophisticated drainage system underneath. According to the Ministry’s statement, Keros, between the bigger islands of Naxos and Amorgos, was one of the most impressive sites on the Aegean Sea in 3000-2000 B.C. — the dawn of Greek civilisation. They also added that prehistoric builders created massive terrace walls that made the 1.3-hectare (3.21-acre) Dhaskalio look like a stepped pyramid. "Almost every possible space on (Dhaskalio) was built on, giving the impression of a single large monument jutting out of the sea," the statement said, adding that the complex is the largest known at the time in the Cyclades island complex, which includes the top tourist destinations of Mykonos and Santorini. More than 1,000 tons of marble were shipped over from Naxos for the work. Project co-director Michael Boyd of Cambridge University told The Associated Press that Dhaskalio appears to have been more than just an ordinary settlement. "It seems to us that it is a central place to which people are drawn, to which expertise and resources are being brought and where activities like the metalworking ... are being centralised and controlled," he said.