Archaeologists Geoffrey Wainwright and Timothy Darvill said the content of graves scattered around the monument and the ancient chipping of its rocks to produce amulets indicated that Stonehenge was the primeval equivalent of Lourdes, the French shrine venerated for its supposed ability to cure the sick.
An unusual number of skeletons recovered from the area showed signs of serious disease or injury. Analysis of their teeth showed that about half were from outside the Stonehenge area.
"People were in a state of distress, if I can put it as politely as that, when they came to the Stonehenge monument," Darvill told journalists assembled at London's Society of Antiquaries.
He pointed out that experts near Stonehenge have found two skulls that showed evidence of primitive surgery, some of just a few known cases of operations in prehistoric Britain.
"Even today, that's the pretty serious end of medicine," he said. Also found near Stonehenge was the body of a man known as the Amesbury Archer, who had a damaged skull and badly hurt knee and died around the time the stones were being installed. Analysis of the Archer's bones showed he was from the Alps.
Darvill cautioned, however, that the new evidence did not rule out other uses for Stonehenge.
"It could have been a temple, even as it was a healing center," Darvill said. "Just as Lourdes, for example, is still a religious center."
The archaeologists managed to date the construction of the stone monument to about 2,300 B.C., a couple of centuries younger than was previously thought. It was at that time that bluestones - a rare rock known to geologists as spotted dolomite - were shipped by hand or by raft from Pembrokeshire in Wales to Salisbury Plain in southern England, to create the inner circle of Stonehenge.
The outer circle, composed of much larger sandstone slabs, is what most people associate with the monument today, particularly since only about a third of the 80 or so bluestones remain. The scientists argued that they were once at the heart of Stonehenge, and closely associated with its healing properties.
As evidence, Darvill said his dig had uncovered masses of fragments carved out of the bluestones by people to create amulets. Any rock carried around in such a way would have had some sort of protective or healing property, he said. He said that theory was backed by burials in southwest England where the stones were interred with their owners.
Today the bluestones are now largely invisible, dwarfed by the huge sandstone monoliths - or "hanging stones" - that were erected later and still make up Stonehenge's iconic profile.
"They are of course quite impressive when you see them," Darvill said. "But in a sense they are the elaboration of a structure which kicked off with the bluestones."
Both archaeologists quoted the 12th-century monk Geoffrey of Monmouth as saying the stones were thought to have medicinal properties. They also said that evidence uncovered by their dig showed that people were moving and chipping off pieces of the bluestones through the Roman period and even into the Middle Ages.
Darvill said he felt the "folklore interest" in the bluestones into modern times suggested some sort of lingering memory of their supposed healing powers.
"That would be for me the single strongest piece of evidence," he said.
Andrew Fitzpatrick, from British heritage group Wessex Archaeology, said Darvill and Wainwright's discovery was "very important" but that the healing theory, while plausible, was not the only one.
"I don't think we can rule out the other main competing theory - that the temple was a meeting point between the land of the living and the dead," he told the British Broadcasting Corp.
The scientists announced their findings Monday, ahead of a documentary due to air on the BBC and the Smithsonian Channel on Saturday, Sept. 27.
