'0578 Holocaust Memorial Baltimore Maryland' photo (c) 2009, Bill McChesney - license: https://creativecommons.org/licenses/by/2.0/

From The United States Holocaust Memorial Museum:

Congress established the Days of Remembrance as the nation’s annual commemoration of the Holocaust and created the United States Holocaust Memorial Museum as a permanent living memorial to the victims. Holocaust remembrance week is April 27–May 4, 2014.

I have multiple Holocaust-related “Best” lists, and you can find them all at The Best Sites For Learning About The Holocaust.