Stonehenge & Avebury
Stonehenge (the first four pictures) is quite well-known. So much so that they don't let you actually walk up to the stones any more. Avebury, not far away, is much larger in area, but not nearly so dramatic. It is a bit older than Stonhenge, and is constructed of unworked stones set in a very large circle - so large that part of the village of Avebury is within the circle.