What an incredible feat of Neolithic engineering!

Lintels

There are only six remaining lintels of the outer sarsen circle in place at Stonehenge, but if it was ever completed, there would have been an unbroken ring of stone, 30m in diameter, suspended 4m above the ground. Each lintel is locked to its supporting upright sarsens with a mortice and tenon joint, and to its neighbours by tongue and groove joints – techniques more commonly found in woodworking.

Further evidence of the care that went into the construction is that the inner and outer faces of the lintels are gently worked to better give the illusion of a continuous ring of stone. Additionally, the tops of the upright stones have been levelled to overcome the effect of the slope on which they are set, resulting in no more than a few centimetres difference in height across the diameter of the circle.