Archaeologists on Monday entered the antechamber of Greece’s mystery tomb in Amphipolis — only to find another wall blocking the tomb’s interior as well as worrying evidence of looting in the form of a suspicious opening.

Before entering the vestibule, or antechamber, the archaeologists had to remove dozens of massive stones which sealed the entrance of the huge burial complex.

“Now the front of the monument has been revealed almost entirely,” the culture ministry said in a statement.

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The tomb’s arched entrance featured a highly original composition for this type of Macedonian tomb, dating from the last quarter of the 4th century B.C. It  was guarded by two headless and wingless seated sphinxes, while the facade boasted fresco imitating the marble of the side walls.

Since the maximum spacing between the columns that form the door frame is 5.4 feet, the archaeologists believe it is very likely that “the door opening was free, with no door panels.”

As the team led by Katerina Peristeri removed debris from the antechamber’s interior, an inlaid composition of marble plaques appeared under the Ionic architrave, fully covering the side walls.

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A pebbled floor was also unearthed in the center and  front of the entrance. It consisted of rectangulars and squares, surrounded by black and white diamond shaped pieces.

Most importantly, the archaeologists unearthed the upper part of a marble blocking wall.

Topped with an architrave decorated with eight-leaved embossed rosettes, the blocking wall showed a suspicious opening on its top left.

The wall, standing about 19 feet from the entrance, would conceal one or more inner chambers, the culture minister said.

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The official statement doesn’t explain much about the hole on the top left, which is seen by many as a strong evidence for tomb raiders plundering the tomb.

Measuring 1.6 square feet, the passage is large enough to let a small man pass through it.

According to reports in Greek media, the archaeologists looked through the window in the blocking wall and saw a second chamber and a wall in the distance, suggesting another door might lead to the tomb’s interior.

At 1,935 feet wide, the mound is the largest tomb ever discovered in Greece.

Archaeologists began excavating it in 2012 and concluded the mound was once crowned by the impressive 16-foot-tall marble lion statue which now stands on a pedestal three miles from the excavation site.

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Indeed, the sphinxes and the lion were crafted in the same workshop from marble brought from the island of Thasso.

Dating between 325 B.C. — two years after the death of warrior king Alexander the Great — and 300 B.C., the tomb lies in the ancient city of Amphipolis, in Greece’s northeastern Macedonia region about 65 miles from the country’s second-biggest city, Thessaloniki.

The city, an Athenian colony, was conquered by Philip II of Macedon, Alexander’s father, in 357 B.C.

Prominent generals and admirals of Alexander had links with Amphipolis. It’s here that Alexander’s wife Roxana and his son Alexander IV were killed in 311 BC on the orders of his successor, King Cassander.

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The burial complex site was possibly built by Dinocrates, a close friend of Alexander best known for building Alexandria in Egypt.

It’s 10 times larger than the lavishly furnished tomb of Alexander’s father, Philip II, which was discovered, untouched, in Vergina, central Macedonia, in the 1970s.

As the excavation continues, speculation aboundS on who is buried in the mound. Putting aside the wild hypothesis that Alexander himself rests there — his tomb has never been found, but all historical records indicate he was buried in Alexandria — theories are now pointing to Alexander’s admiral Nearchos, as well as Roxana, his son Alexander IV and his sister Cleopatra.

“More than likely we will be surprised and find the unexpected,” University of Bristol Nicholas Saunders, author of “Alexander’s Tomb,” told the Greek newspaper Ethnos.