After he became ruler in 1740, Frederick the Great personally planned the buildings surrounding this square (which has a huge parking garage cleverly hidden beneath the pavement). The area received the nickname "Forum Fridericianum," or Frederick's Forum. On May 10, 1933, Joseph Goebbels, the Nazi minister for propaganda and "public enlightenment," organized one of the nationwide book-burnings here. The books, thrown on a pyre by Nazi officials and students, included works by Jews, pacifists, and Communists. In the center of Bebelplatz, a modern and subtle memorial (built underground but viewable through a window in the cobblestone) marks where 20,000 books went up in flames. The Staatsoper Unter den Linden (State Opera) is on the east side of the square. St. Hedwigskathedrale is on the south side of the square. The Humboldt-Universität is to the west.