Archaeologists discovered a rare Roman limestone sarcophagus containing a headless skeleton at the site of an historic London church, authorities said Friday.

The find dates to about 410 A.D. and lay 10 feet below the grounds of the St. Martin-in-the-Fields church near central London's busy Trafalgar Square, outside the boundaries researchers had established for London's Roman city walls.

"The find has opened up an exciting new area of Roman London for study," said Taryn Nixon, director of the Museum of London Archaeology Service.

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Excavators and archaeological teams discovered 24 medieval burial sites in the area above and around the Roman sarcophagus during work on the church grounds this summer.

The discovery lies in view of the National Gallery art museum and the square, which is often congested with tourists.

The sarcophagus was made from a single piece of limestone from Oxfordshire or Northamptonshire, about 60 miles northwest of London, researchers said.

The skeleton, headless and missing fingers, is a 5-foot-6-inch male who died in his 40s. Researchers speculated that Victorian workmen building a sewer stumbled upon the sarcophagus and took the head.

The site is about a mile west of the boundary of Roman London established by researchers, said Roman history expert Hedley Swain.

Archaeologists made two similar finds in London during the 1970s and once at Westminster Abbey during the 19th century.