LONDON – Scientists scouring the area around Stonehenge said Thursday they have uncovered a circular structure only a few hundred yards from the world famous monument.

There’s some debate about what exactly has been found. The survey team that uncovered the structure said it could be the foundation for a circle of freestanding pieces of timber, a wooden version of Stonehenge.

But Tim Darvill, a professor of archaeology at Bournemouth University in southern England, expressed skepticism, saying he believed it was more likely a barrow, or prehistoric tomb.

Darvill did say that the circle was one of an expanding number of discoveries being made around Stonehenge, which “really shows how much there is still to learn and how extensive the site really was.”

“In its day Stonehenge was at the center of the largest ceremonial center in Europe,” he said.

The stonehenge that is visible today is thought to have been completed about 3,500 years ago, although the first earthwork henge on the site was probably built more than 5,000 years ago.

Although antiquarians have been poking around the area since the 18th century, excavations are now tightly restricted. So archeologists have been scanning the surrounding fields and pastures with magnetic and radar sensors pulled across the grass by tractors or quad bikes.

The new structure was found when scans identified a cluster of deep pits surrounded by a ring of smaller holes about a half-mile from Stonehenge.

University of Birmingham archaeologist Henry Chapman said he was convinced the small holes were used to secure a circle of wooden poles which stood “possibly three or more meters (10 or more feet) high.”

The whole area around Stonehenge is dotted with prehistoric cemeteries — some of which predate the monument itself — and new discoveries are made occasionally.