This is the largest of the famous circle terraces at Moray in Peru. Moray is thought to have been an Inca agricultural station. The steps used to climb down to the center (visible here as zig-zags) were built by the Incas into the sides of the terraces as jutting stones in order to maximize the available farming surface. You can get a sense of the massiveness of the circles by taking note of how tiny the people look.
You can view more featured photos at my Photo of the Day Collection.