The Callanish Stones (Calanais in Gaelic) have stood by Loch Roag for between three- and four-thousand years, and possibly as long as 5,000 years. The tallest central stone is almost five metres high. And, although narrow, it weighs some five tonnes. From the circle, an avenue of double standing stones extends to the north, with single stone lines following the other cardinal points. Most of the stones are of Lewisian gneiss. Their pale grey and white colouring gives them a lifelike vibrancy.