Amber Room
Shortly after the beginning of the German invasion of the Soviet Union in World War II, the curators responsible for removing the art treasures in Leningrad tried to disassemble and remove the Amber Room. However, over the years the amber had dried out and become brittle, making it impossible to move the room without the amber crumbling. The Amber Room was therefore hidden behind mundane wallpaper, in an attempt to keep German forces from seizing it, but the attempt to hide such a well-known piece of art failed.