During WW2 the Germans built a wall of steel and concrete, the Atlantikwall, from Northern Norway to the Spanish border. Started in 1941 but never completed due to the D-Day landings, the wall was built to stop an invasion from England and to protect a vast array of Hitler's secret weapons. This website shows what's still left to see 70 years on, including many of the defences from Dunkirk to Bordeaux.
Also many defence sites in Britain with airfields, radar sites and camps from Scotland to Cornwall.
© 2013 Richard Drew