I bought this book in a little store outside of the Cathedral. It has turned out to be a fascinating read. I would like to be able to read his other books, but unfortunately they are not translated.
He makes a case for how and why the cathedral was built. He raises the question of why so many Gothic cathedrals were built starting in the same time period, as well as the question of how this Cathedral was funded, designed and who the master builder might be.
I have no idea how valid his theories are about the Templars, but he makes an interesting argument. The book left me wanting more, which is rare these days!