Sergei Rachmaninov's third piano concerto begins with a wonderfully simple melody. "I wanted to sing the melody on the piano like a singer would. That's all!", he said later. But the work, also known as the "Elephant Concerto", is one of the most difficult for pianists and contains more notes per second than any other major concerto of its kind. Rachmaninov himself played the premiere in America in 1909 and practised it on the Atlantic crossing because he only finished it at the last moment. Of course, this is no longer noticeable in the work today - it is one of the most popular and most frequently performed piano concertos of all time.
(The Digital Concerto Introduction is only in german available)