Very interesting book detailing how it all started with the underground quarries whilst Paris was being built, then how these hollow vacuums made it unsafe for the buildings & roads above ground, they then had to be all mapped out, and made safer. And this all started 300 years ago, then it goes to explain with great pics how tunnels have been used for many things since from the monks brewing beers to shelters for the Germans. Also the various marks & meanings, graffiti going back 100’s years.