The Thornborough Henges are an enigmatic complex of three large henges in North Yorkshire, connected by two long avenues.
They form a pair of alignments which interact with the surrounding landscape and the rising of certain stars on the horizon in the megalithic era.
This presentation below shows firstly how the Henges are laid out using simple geometry and Pythagorean right-angled triangles.
Using a combination of Google Earth and Stellarium imagery, it then shows how the various elements interact.
The presentation below was prepared as notes for a talk never given.
The images are largely self-explanatory, and reveal the underlying geometry of the Thornborough Henges and surrounding landscape.