How was your experience?
Mark is a wonderful tour guide. He has amazing information, is educational, has funny stories, and teaches you how to enjoy the cathedral on your own. The tour is all outside so be prepared for the weather. I went on a cold day and by the end I was miserable. If I had dressed more appropriately for the weather I would have enjoyed it more. Also binoculars are a MUST. The tour would not been nearly as fun without them.