Giant stone circles in the MIddle East

First noticed a centurty ago, but only now being studied:

Archaeologists in Jordan have taken high-resolution aerial images of 11 ancient "Big Circles," all but one of which are around 400 meters (1,312 feet) in diameter. Why they are so similar is unknown but the similarity seems “too close to be a coincidence" said researcher David Kennedy...

Their purpose is unknown, and archaeologists are unsure when these structures were built. Analysis of the photographs, as well as artifacts found on the ground, suggest the circles date back at least 2,000 years, but they may be much older...

The purpose of the Big Circles is a mystery, Kennedy said. It seems unlikely that they were originally used as corrals, as the walls were no more than a few feet high, the circles contain no structures that would have helped maintain an animal herd and there's no need for animal corrals to have such a precise shape, he said.

A gallery of photographs (including several at ground level) is here.