Hidden landscapes at Stonehenge revealed

The mystery of Stonehenge -- how it was built and what it was for -- has kept scholars occupied for centuries. Now it seems they've got even more work because there are more stones -- lots more.

"New" 4,500-year-old relics have been found using the latest technology: ground-penetrating radar that can see beneath the surface, reports CBS News correspondent Mark Phillips.

The scientists call it the Hidden Landscapes Project, and it has revealed hidden landscapes beyond their wildest imaginings -- a perimeter of standing stones -- and many times the size of neighboring Stonehenge.

The stones, it seems, where erected to delineate an area of special significance -- some sort of temple or public forum, or both. But the radar also reveals that the stones were then knocked down and covered with an earthen mound. There's plenty here to occupy archaeologists for the next several centuries, and they want more.

CBS News met Henry Chapman, an archaeologist with the team, on the project site late last year.

"It's sort of the sweet shop problem," Chapman said, "that, when you present it with loads of information, kinda think, so I want some more."

Scientists are pretty sure they know what Stonehenge was for -- it's essentially a large clock that tracks the seasons through the movement of the sun, a useful tool for a stone-age agricultural society.

But the point of the new discovery? Well, they know it's probably important, but they haven't a clue, really.

"The most important things that's been discovered in the last 20 to 30 years anywhere, it was completely unsuspected and it gives us a whole new chapter in the story," archeologist Nick Snashall said.

Stonehenge has been drawing visitors since the dawn of time. It's combination of scale and mystery has been irresistible, even to some of the most powerful people in the world. President Obama passed that way on a recent U.K. visit.

Now science has provided more to ponder.

Other modern techniques -- laser scanning, magnetic mapping -- can reveal even more about a fascinating place we may never fully understand. But what the archaeologists really want to do next is dig.