Its Vienna premier featured the composer's student Carl Czerny as the soloist, due to the composer's deafness.  
In this work's long first movement, the first of the three opening orchestral chords oddly lacks a B flat note, and each chord is followed by a short cadenza.  Its second movement, in B major, ends with a long pedal point beginning with the French horns that sees a semitone drop from B major to B flat on the bassoon lead directly into the third movement, which is back in E flat major.  Its Vienna premier featured the composer's student Carl Czerny as the soloist, due to the composer's deafness.  FTP name this work for solo keyboard instrument and orchestra, the last such work written by Ludwig van Beethoven.
In this work's long first movement, the first of the three opening orchestral chords oddly lacks a B flat note, and each chord is followed by a short cadenza.  
"Emperor Concerto" or Beethoven's Piano Concerto No. 5 [require "Beethoven" before mention]