I don't know what it is about them John........... I believe in Franceicon they are trying to preserve them now due to the slave labour used to build them, Little is known but the there was a special unit (uniforms too) that were the builders of them.......

I guess its the part of History that still reamains that gets me, a grim reminder for sure but fascinating all the same, Certainly ahead of there time when it comes to shuttering a 3:2:1 mix.