The idea came to me when I was sitting in Notre Dame Cathedral in Paris. It was one of those moments you experience when traveling: the feeling of mystery, intrigue and wonder. I was in awe; architectural feats of high arched ceilings, intricate artwork details and masonry surrounded me. It was hot and sticky outside, yet the inside of the cathedral felt cool, dusty and grey, like a scene from an old spy movie. With all of the nooks, passages and obscure locations, I couldn't help but wonder how many secret messages and clandestine signals had been etched into the history of this inviolable place by Cold War spies. Having personally employed many of these "spy" tactics as a SEAL, the cathedral began to look more like a canvas of opportunity. A bit obvious and grandiose and, yes, even a bit sacred for such seemingly nefarious acts, but inspirational nonetheless.