Preeminent among megalithic monuments in Great Britain is Stonehenge.
Enclosed by a circular ditch 300 feet in diameter, stones are arranged in 4 series. 2 outermost form circles. The 3rd is a horseshoe shape. The innermost is ovoid in form. Some original uprights remain.
Within the ovoid lies the "Altar Stone."
It was probably a bronze age burial site. Nothing is known for sure.