What is the greatest work of Beethoven?

Ludwig van Beethoven's greatest work is widely considered to be his Symphony No. 9 in D minor, Op. 125. It is renowned for its emotional depth, musical complexity, and introduction of the human voice in the final movement. The symphony premiered on May 7, 1824, and is also known as the "Choral Symphony" due to its inclusion of vocal soloists and chorus in the concluding section.