George Gershwin - "An American in Paris"

He moved to Paris intending to study with Nadia Boulanger, but she refused him. He subsequently composed An American in Paris, returned to New York City and wrote Porgy and Bess with Ira and DuBose Heyward. Initially a commercial failure, it came to be considered one of the most important American operas of the twentieth century and an American cultural classic. From Wikipedia