The Piano Concerto No. 1 in B-flat minor, Op. 23 was composed by Pyotr Ilyich Tchaikovsky between November 1874 and February 1875. It was revised in the summer of 1879 and again in December 1888. The first version received heavy criticism from Nikolai Rubinstein, Tchaikovsky's desired pianist. Rubinstein later repudiated his previous accusations and became a fervent champion of the work. It is one of the most popular of Tchaikovsky's compositions and among the best known of all piano concerti.