Similarly influential were Field's early piano concertos, which occupy a central place in the development of the genre in the 19th century. Already the earliest of these works show competent and imaginative orchestration, and bold, original piano writing. One interesting trait of his piano concertos is their limited choice of keys: they all use either E-flat major or C major at some point (or both, in the last concerto's case). Composers such as Hummel, Kalkbrenner and Moscheles were influenced by these works, which are particularly notable for their central movements, frequently nocturne-like. Some of the less known works were also historically important: particularly the piano fantasies, in which Field pioneered the Romantic large scale episodic structure.