Washington (AP) New research indicates that Stonehenge in England served as a burial ground far longer than first believed.

Researchers say the dating of cremated remains shows that burials took place as early as 3000 B.C., when the first ditches around the monument were being built.

They say those burials continued for at least 500 years, when the giant stones that mark the mysterious circle were being erected. In the past many archaeologists had thought that burials at Stonehenge continued for only about a century.

The research is supported by the National Geographic Society, which discusses Stonehenge in its June magazine and will feature the new burial data on the National Geographic Channel this Sunday