 Polish flags and other symbols were confiscated . The war on the Polish language included the tearing down of signs in Polish and the banning of Polish speech in public places . Persons who spoke Polish in the streets were often insulted and even physically assaulted . The Germanization of place names prevailed . Many treasures of Polish culture – including memorials , plaques and monuments to national heroes ( e.g. , Kraków 's Adam Mickiewicz monument ) – were destroyed . In <unk> , all Polish monuments and plaques were torn down . Dozens of monuments were destroyed throughout Poland . The Nazis planned to level entire cities . 
