Fortress: As early as prehistoric times settlements were protected against attack by fortifications. In the Middle Ages walled cities and Castles and Palaces took over this function; one of the most protected medieval fortresses is Hohensalzburg Castle. Fortresses also had to be constructed to withstand attacks with guns and cannons (improvement and expansion in Vienna due to the Turkish sieges 1529 and 1683, and in Graz). New fortresses were constructed in the 17th and 18th centuries (Theresienstadt, Kufstein, Franzensfeste in South Tyrol). In the 19th century Austria reinforced the construction of the rectangle of fortresses Mantua- Peschiera- Verona- Legnano to defend Lombardy, as well as the Fortress Przemyśl before World War I in Galicia; however, the efforts did not live up to expectations. Hitler's propaganda of Austria as an "Alpine Fortress" in the last weeks of World War II in 1945 proved unfounded.