Bratislava has always been the city at the border. The city itself and its surroundings were fortified from the medieval ages to the present time. The latest fortress system was built just before WW2 by a democratic Czechoslovakia to repel Hitler's invasion. Due to the political decisions from September 1938, this well prepared defense system could not have been used and Hitler invaded this land without a fight. Once the war had come to an end, the communist regime raised up the Iron Curtain which divided Europe. Bratislava, as part of the eastern block received another "defense system". This one prevented citizens from travelling freely to western countries. The edge of the city, with massive bunkers, became part of a strictly patrolled "no-trespass area". Due to the fact that for more than forty years, no one could go near the border, our technical heritage - the Czechoslovak fortress system, became forgotten.