Photograph by Saul Loeb, Getty Images

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President Barack Obama tours Stonehenge in Wiltshire, England, on September 5.

Photograph by Saul Loeb, Getty Images

Obama Visits Stonehenge, Whose Monoliths Still Hold Mysteries

U.S. president makes a pitstop on his way back from NATO summit.

Barack Obama stopped by Stonehenge Friday on his way back home from the NATO summit in Wales.

"How cool is this!" the U.S. president said amid a 20-minute walk around the famous standing stones in Wiltshire, England, according to the pool report. "Knocked it off the bucket [list]!" (See National Geographic's Stonehenge photos.)

People have wondered for centuries why the eerie 4,500-year-old megaliths were built. Theories have held that Stonehenge was an astronomical calendar, a place of healing, or a marker for supposedly magical energy lines in the ground, perhaps built by the Druids. (Read about Stonehenge in National Geographic magazine.)

Archaeologist Mike Parker Pearson and his colleagues at the Stonehenge Riverside Project, whose research was funded in part by the National Geographic Society, have unearthed some clues about the site. (Take a Stonehenge quiz.)

For instance, we now know that Stonehenge—a UNESCO World Heritage Site—was the largest cemetery of its day, and that it had held religious significance for a long time.

The location was a huge settlement area for hunters and gatherers, and it seems to have been occupied on and off for something like 4,000 years before Stonehenge itself was ever built, Pearson told National Geographic in 2013. (See our 3-D interactive of Stonehenge.)

"We think that long before Stonehenge, this location was already a special place," he said. "These hunters and gatherers may have been the people who first recognized this special feature in the land where the Earth and the heavens were basically in harmony."

Obama seemed to have also been taken with the place: "It's spectacular," he told the press pool.

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