The opening theme of the third piano concerto is in C minor, positively drenched in C minor. The string section ply the C minor triad ascending, and the C minor triad (plus a few passing notes all in the C minor tonality) descending:
Piano Concerto No. 24 in C Minor, said to have been played by Beethoven in public concerts. Mozart's concerto also begins with the three notes of the C minor triad, but the two works are very different past that.
The concerto was composed in 1800 and premiered in 1803 with Beethoven as soloist. As usual with Beethoven, he had no time to write down the solo part so he wrote a few scribbles on music paper to help him remember the music and played it mostly from memory. On the day of the concert he rose from his bed at five in the morning to copy out the parts for trombone and then made a hasty trip to the concert hall for rehearsals. The concert also had his 2nd Symphony and his oratorio Christ On The Mount Of Olives on the program as well as a repeat of his 1st Symphony heard at a previous concert. This was a very busy time for the thirty-year old composer, fresh from his studies and ready to make his mark on the world.