Site archaeologist Aikaterini Peristeri has voiced hopes of finding "a significant individual or individuals" within.
Greek websites enthused that it could hold the long-sought grave of 4th-century B.C. warrior-king Alexander the Great — thought to lie in Egypt.
A Culture Ministry statement Thursday said the partly-excavated mound has yielded a "very remarkable" marble-faced wall from the late 4th century B.C. It is an impressive 500 meters (yards) long and three meters high.
But the ministry warned it would be "overbold" to link the site near ancient Amphipolis, 370 miles (600 kilometers) north of Athens, with "historic personages" before the excavation is completed.
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