The people of Jordan refer to these circles simply as 'The Big Circles.' That's quite a pedestrian name for such a puzzling mystery. These massive circles, which can be up to 1500 feet in size, are made from stones, and the walls are three feet high.
Some have speculated that they were enormous pens for animals, but they don't have any visible exits or entry points. The reason for their construction has been lost in the 2000 years since they were made.