Beethoven was a dazzling pianist, so it’s no surprise that his five concertos featured the instrument in the lead role. While his first two works reveal ideas gleaned from Mozart and Haydn, by the time he wrote his third he'd forged his own voice, moving to a minor key for his third, completed in 1803. There, he shifted away from Classical trademarks and moved toward Romanticism, a transformation mastered with his fourth concerto a few years later.