The first time I went to Chartres, there was a Scottish guide named, if I remember correctly, Muller. It's possible that he knew more about his subject than any other guide I have ever encountered. He was also wry and witty, which made the tour even more fun. From what I understand, he went to the cathedral in his youth and it became his lifelong passion: He educated himself about it. At some point, he was declared a "Tresor de France."I was going to take the French-language tour because I was trying to develop my ear for the language. But I'm glad someone convinced me to take Muller's English-language tour.
I do believe I overheard much of his tour when we last visited over fifteen years ago. The windows he was so passionate about have been restored but we did not know that the whole of the interior is now being plastered and painted in authentic materials to make it look as bright and beautiful as it did when it was first built. What a revelation!