WILTSHIRE, England, Sept. 5 (UPI) – President Barack Obama visited the Stonehenge prehistoric monument in Wiltshire, England, Friday after the NATO summit in Wales concluded.

After a two-day conference in which NATO strengthened ties with eastern European members, denounced Russian incursions into Ukraine and called for a unified effort to eliminate the Islamic State, Obama helicoptered to Boscombe Down Air Base, near Wiltshire, for an unscheduled guided tour of the ancient and massive stones, believed to have been installed on the Salisbury plain around 2400 B.C.

“How cool is this? Spectacular. Knocked it off my bucket list,” Obama said.

He will return to Washington today.