Today (15th January) is the anniversary of the death of a great german woman: Rosa Luxemburg, a Marxist theorist, philosopher, economist and revolutionary socialist killed in 1919 when she was 48. She was also the co-founders of the Communist Party of Germany, together with Karl Liebknecht.
She had, together with other socialists, a monument with the 33 victims of the Spartacus Uprising - including the murdered Karl Liebknecht. The monument, built in 1926 was destroyed by Nazis in 1933. Until 1933, in the cemetery at the Monument to the Revolution there were annual parades and memorial services in honor of Lenin, Liebknecht and Luxembourg (so-called "LLL-wochen ).
The actual monument at the entrance of the monument with the stone of "Die Toten Mahnen Uns" (the dead admonish us) has been built in 1951 and it hosts the socialists and the communists and honorary people who had been deserved to the socialist idea made the SED 's view.
More infos: WIKI (german)