Aerial image of Scotland, UK: Callanish Standing Stones, Callanais, Isle of Lewis and Harris, Outer Hebrides. a group of stones that date from the late Stone Age and early Bronze Age. The 13 primary stones (local Lewisian gneiss) form a circle about 13 m in diameter, with a long approach avenue of stones to the north, and shorter stone rows to the east, south, and west. The overall layout of the monument recalls a distorted Celtic cross. Inside the circle is a central burial chamber of Neolithic age.