http://www.megalithic.co.uk/article.php?sid=2146414126

Overall I found this publication highly readable, being both informative and slightly controversial. A basic knowledge of the period would help the reader but most MegP devotees should have this. A basic knowledge of trigonometry would also help, but the book has enough illustrations (photographs, line drawings, diagrams and computer-aided pictures) to overcome the problem.
The author has obviously done a lot of research, but more importantly has put in a lot of leg-work visiting the sites mentioned in the book and has actually tried the experiments using only the materials available to megalithic peoples. When someone has done (or tried to do) something, you get an added depth to the experience and this certainly comes across in Jon’s writing. Page 11 has a marvellous example, when attempting to view the exact point on the horizon where the sun rises/sets. Even on a clear day this is often impossible due to the haze, something I also know through bitter experience.
The one thing that makes this book a winner is the fact that it’s central theory is not a house of cards. The various parts are not all required to prove that Stonehenge was a geocentric “planetarium” (or whatever the solar equivalent is) and equally you can accept all the parts but reject the final conclusion....
Highly recommended to anyone with an interest in Stonehenge.
Blatant plug (sorry)