Archeologists working in Greece say they've unearthed an apparent entrance to a tomb dating to around the end of the reign of Alexander the Great.
Alexander, whose empire spanned from modern Greece to India, died in 323 B.C.
The Greek tomb, which experts believe would have belonged to an important figure, dates to sometime between 325-300 B.C.
Greece's Prime Minister Antonis Samaras, visiting the Amphipolis excavation site in northern Greece, said the finding "is clearly extremely important."
Some historians have speculated the tomb could be the resting place of one of Alexander's military commanders or perhaps a family member.
"It looks like the tomb of a prominent Macedonian of that era," an official of the Greek culture ministry said.
Alexander's empire quickly dissolved into opposing factions after his death, and in Amphipolis, the former colony of Athens conquered by Alexander's father Philip II in 357 B.C., Alexander's wife Roxana and his son and heir to the throne, 12-year-old Alexander IV, were killed by a Macedonian general.
It's possible the burial complex was constructed for either or even both of them, historians say.
There is also speculation it may have been intended as the final resting place for Alexander's body, stolen on its way back to Greece after his death in Bablyon in modern-day Iraq. It is thought he was buried somewhere in Egypt.
Other ancient tombs have been unearthed in the region, notably that of Philip II, Alexander's father, which was discovered in 1977.
"The land of Macedonia continues to move and surprise us, revealing from deep within its unique treasures," Samaras said.
"Regarding the key question, the excavation will reveal the identity of the deceased," he added.
Two years of excavation work have uncovered a massive burial mound surrounded by a wall of marble 1,600 feet long and 10 feet high.
The marble would have been brought from the island of Thassos, the archaeologists say, and it has been suggested the tomb was designed by a famous architect of the time named Dinocrates, a known friend of Alexander's.
A broad road leads to the recently uncovered entrance, where two headless sphinxes stand guard.
Archaeologists said they were hopeful they could gain entrance to the tomb by the end of August, as work is ongoing under heavy police presence to protect the tomb and any possible contents.
"The excavation will continue at a pace dictated by the finding as well as the scientific ethics," the Greek prime minister said.
