Perhaps the oldest structure was Trethevy quoit on Bodmin Moor. This is a dolmen, a chamber made from huge stones thought to date to the end of the Neolithic (Late Stone Age), about 5,500 years ago. There are a few in Britain, some having shown evidence of burials within them but they may have also had other purposes such as territorial markers. No one really knows with certainty the original purpose of these chambers, but they are also found as far away as Korea and India.
On the same side of the moor one can find the Hurlers, a row of three (or possibly four) stone circles and outlying stones, which may date to the Bronze Age or may be older. They lie in a SSW-NNE alignment.
We were very lucky to visit them whilst an excavation was taking place to uncover a 'pavement' of white quartz stones, which appears to link two of the circles and runs in the same orientation. The quartz structure has only been uncovered in modern times once before, in 1938, and will be covered over again once the project is completed. The local community was assisting with the dig, which was tied in to a study of the astronomical orientations of the site that is being conducted by the Roseland Observatory. It's interesting to think what the Hurlers must once have looked like. The stones in the circles show evidence of having been hammered to shape and the pavement of quartz must have glowed and twinkled in certain light conditions.