'Hidden, Forbidden & Off-Limits' By Steve Higgins

The book also includes a "bunker bucket list" chapter, which offers a glimpse into some of the most fascinating underground places in the world such as the Cheyenne Mountain Complex in Colorado, France's Maginot Line and the catacombs under Paris, and the impressively preserved Diefenbunker in Canada.

'Hidden, Forbidden & Off-Limits' offers a unique perspective, not just about the history of these underground places, but also about Steve's personal adventure, the situations encountered and the people met along the way.