A person visits the troglodythic underpass at Breze Castle near Saumur, western France, on July 23, 2012. Fifteen years after its public opening, the Breze castle, the largest underground fortress in Europe, has successfully optimized its amazing underground network, “A castle in the castle”, to boost its traffic and enter the list of great sites of the Loire valley with Chambord or Chenonceau. AFP PHOTO/ALAIN JOCARD (Photo credit should read ALAIN JOCARD/AFP/GettyImages)