Lincoln Memorial, 1939
This from Wikipedia:
"In 1939, the Daughters of the American Revolution (DAR) refused permission for Anderson to sing to an integrated audience in Constitution Hall. The District of Columbia Board of Education declined a request to use the auditorium of a white public high school. As a result of the ensuing furor, thousands of DAR members, including First Lady Eleanor Roosevelt, resigned.
The Roosevelts, with Walter White, then-executive secretary of the NAACP, and Anderson's manager, impresario Sol Hurok, then persuaded Secretary of the Interior Harold L. Ickes to arrange an open air Marian Anderson concert on the steps of the Lincoln Memorial. The concert, commencing with a dignified and stirring rendition of "My Country, 'Tis of Thee" attracted a crowd of more 75,000 of all colors and was a sensation with a national radio audience of millions."