Mannheim is the second-largest city in the German state of Baden-Württemberg.
During Tchaikovsky's lifetime it was part of the Grand Duchy of Baden, and from 1871 part of the German Empire.
Tchaikovsky in Mannheim
Tchaikovsky spent two days in Mannheim during mid/late June 1870, attending a music festival celebrating the centenary of the birth of Ludwig van Beethoven.
He found the festival programme "most interesting" and the quality of the various performances of the great composer's music "marvellous", and he was especially struck by the Missa Solemnis, which, hearing it for the first time, he described as "a musical composition of the highest genius" .