Scientists are closing in on the lost tomb of Alexander the Great by using an array of ground-penetrating detection technologies.
The mausoleum of the Macedonian king, who carved out one of the greatest empires ever, has eluded discovery for 1,500 years.
Now a team from the University of Patra in Greece is systematically probing the cemetery quarter of the Egyptian city of Alexandria for telltale signs of what would be the archaeological discovery of the century.
The scientists, led by Stavros Papamarinopoulos, head of the geophysics laboratory at Patra, identified six possible ancient burial sites in their first season.
None was Alexander's tomb, but, Dr Papamarinopoulos said, if they were found to date from classical times they would indicate that the team is on the right track. "This is possibly the greatest prize in archaeology, but we have to be realistic. This is only the first step," he said.
Alexander died aged 33 in Babylon in 323BC. His army commander, Ptolemy, brought his remains to Alexandria, which the king had founded. There, Alexander was placed in a glass coffin and interred in a mausoleum called the Soma , which was eventually surrounded by tombs of the Ptolemy dynasty.
Some 600 years after Alexander's death, the site of the tomb was no longer recorded.
Dr Papamarinopoulos is working on a theory by Italian archaeologist Achille Adriani that narrows the search to an area covered by foreign cemeteries.
The team deployed an array of geophysical techniques - including ground-penetrating radar, microgravity and electromagnetic probing - to pinpoint geometric shapes that might be tombs buried in the landscape.
French archaeologists found that the ancient ground level is just 1m below what it is today, making the hunt for ancient tomb openings easier. The scientists, who published their first results in the latest edition of the journal Archaeological Prospection , hope to continue their hunt next year.