In 2010 France awarded her the Legion of Honour.
"It was the very special combination of a unique voice and intelligence of interpretation that made her so special," the Vienna State Opera said.
La Scala opera house said the music world had "lost a luminous and inimitable personality".
Ludwig was married to the Austrian bass-baritone Walter Berry for 13 years. They divorced in 1970 and two years later she married French actor and director Paul-Emile Deiber, who died 2011.
German mezzo-soprano Christa Ludwig during a photocall at the 47th Midem in Cannes, France, 26 January 2013
IMAGE COPYRIGHTEPA
image captionChrista Ludwig was born into a musical family in Berlin in 1928