Beethoven’s creation for piano and orchestra concertos is commonly considered to be a corpus of five works, although there is a «concerto nº 0», from his adolescence, but only the piano part remains. Beethoven was famous for his great skill at improvising on the keyboard and number 1 and 2 were composed in his youth and follow 18th century aesthetics. The turning point comes with nº 3, a formal advance the composer was fully aware of. There is general consensus in that the piece which is most original and well-rounded is nº 4, from around 1808. The fifth, perhaps the most famous and well-balanced, is from 1809, and was immediately known as “Emperor” which clearly opposed the idea of the composer. Beethoven did not actually complete any other of his concertos in the remaining eighteen years of his life. He did not finish nº 6, whose first movement has been completed by the famous British musicologist Nicholas Cook.