ROUGH CUT (NO REPORTER NARRATION)<br/> <br />After wrestling with threats ranging from Russia to Islamist insurgency in the Middle East, U.S. President Barack Obama took a break from a NATO summit to visit Britain's prehistoric Stonehenge monument on Friday.<br/> <br />"How cool is this?" Obama said as he wandered starry-eyed in his shirt sleeves among the towering stone megaliths.<br/> <br />"It's spectacular," said Obama, as he gazed at the circle of towering megaliths while sheep grazed in a nearby field. "Knocked it off the bucket list," he said, using a term for must-do experiences before one dies.<br/> <br />Built between 3,000 and 1,600 BC, the stone circle may have been a temple, a burial ground, an astronomical calendar or all three, scholars say.<br/> <br />No one knows for sure either how ancient Britons got the stones, which weigh up to 45 tones, to the site or what they used them for.
