Calanais Standing stones
These stones are made of Lewisian Gneiss, a type of white granite and one of the oldest stones in the British Isles. It is one of the most complete stone circles and is in the shape of a Celtic cross. This is somewhat intriguing as the stones predate the Eygptians. The shape and the cairn in the centre have caused some to speculate about aliens etc. However, the most likely use would be a calender.
There are several smaller circles nearby.
We went on a Sunday so the visitor centre was closed but we were still able to walk up to the stones. Everything is closed on the Sabbath on Lewis.