1.) The Great Pyramid of Giza - background for the following links
2.) Chris Dunn's website
3.) Margaret Morris's response to Dunn
4.) Another response to Dunn, this time from Alan Alford
and finally, pages 20-22 of Crecy
Aside from Crecy, I haven't read Dunn's book and these articles thoroughly, but it's a good idea to maintain a healthy skepticism about these topics. Then again, we may just be rediscovering lost knowledge again and again. Personally, I think the Crecy excerpt sums up my view of people and technology from previous eras.