Stone circles are surrounded by myth and mystery, not least because of their age and incredible dimensions. Keeping this in mind, then add the spectacular scenery of the Lake District, it is not difficult to see the attraction of Castlerigg (or Druid's Circle).

Thought to have been in existence for at least 5000 years, this arrangement consists of 38 un-hewn boulders set out in a circle of about 100ft (30.3M) in diameter, that is slightly flattened along the north east perimeter. Most unusually, there is a further group of 10 smaller stones forming a rectangle (known as a cove) and placed inside the circle at its eastern edge. Although some of the stones have fallen over time, many remain standing to a height of more than 5ft (1.5m), with the largest being 8ft 3ins (2.5m) and weighing about 16 tons.

Was Castlerigg deliberately sited with the Cumbrian peaks as a magnificent backdrop, as suggested by A L Lewis? Was it used for religious ceremonies? Did early tribes meet up here for an annual gathering? Could it have been some kind of trading post? Any of these functions could provide a reason for the erection of the stone circle, and maybe Castlerigg has been the focal point for all of them. However, Alexander Thom carried out a precise survey of the site and, using mathematical equations, deduced that this location had been carefully selected as a place to observe the sun and moon rise and fall behind the distant peaks. In fact, he elaborated on this theory by suggesting that the stone ring was the means by which the harmony of the Earth, the heavens and the human mind was reduced to mathematics.

Of course, we are never likely to discover the definitive reason for building these hugely impressive circles, and we can only imagine how such a feat was accomplished without the aid of modern day mechanics. However, the experience of being in the midst of a stone circle can be quite thought-provoking, or even spiritual, which is possibly why they have become widely associated with religion in some form.

If you find yourself in the Keswick area, go and search out this amazing site - you will not be disappointed. On a beautiful day, it is a delight to walk across the open field and investigate Castlerigg, overlooked by the spectacular peaks of Skiddaw and Blaencartha.