WASHINGTON - The secret of Stonehenge has been solved: The mysterious circle of large stones in southern England was a burial ground for almost five centuries, and probably holds the remains of a family that long ruled the area, new research concludes.

Based on radiocarbon-dating of cremated bones up to 5,000 years old, scientists with the Stonehenge Riverside Archaeological Project said they were convinced that the area was built and grew as a "domain of the ancestors."

"It's now clear that burials were a major component of Stonehenge in all its main stages," said Mike Parker Pearson, archaeology professor at the University of Sheffield in England and head of the project. "Stonehenge was a place of burial from its beginning to its zenith in the mid-third millennium B.C."

The finding marks a major rethinking of Stonehenge, which in the past was believed to be a burial site for only a century.

A combination of factors - the radiocarbon dating, nearby excavations that have revealed a once-thriving "domain of the living," and the fact that the number of cremated remains appeared to grow over a 500-year period - convinced researchers the site was used for a long time and most likely was a burial ground for one ruling family.

Parker Pearson said the discovery of a mace head - long a symbol of authority in England that still serves the same function in the House of Commons - supports the theory that it was the province of a ruling family.

He said family members for as many as 30 to 40 generations were buried there, with each generation having more members.

The team also excavated homes nearby at Durrington Walls, which they said were especially well-preserved and appeared to be seasonal dwellings related to Stonehenge.

"It's a quite extraordinary settlement," Parker Pearson said. "We've never seen anything like it before."

The village had at least 300 and as many as 1,000 homes, which apparently were occupied in the midwinter and midsummer. Broad avenues leading from Stonehenge to the River Avon, as well as another leading to the river from a circle of wooden pillars close to the village, were both oriented to the winter and summer solstices.

The research was supported by the National Geographic Society, which features Stonehenge in the June issue of its magazine.

The latest Stonehenge research marked the first radiocarbon dating of cremation remains at the site. The burials dated by the group were excavated in the 1950s and have been kept at the nearby Salisbury Museum. In the 1920s, an additional 49 cremation burials were dug up at Stonehenge, but all were reburied because they were thought to be of no scientific value, according to the researchers.

As many as 240 people were buried within Stonehenge, the researchers said.

The stone pillars at the site have long fascinated archaeologists and the public. The smaller ones were transported great distances from Wales, while the larger stones are from more local sources.