Background: Harpo was born on November 23, 1888 in Manhattan. He grew up in a neighborhood now known as Carnegie Hill on the Upper East Side of Manhattan, on East 93rd Street off Lexington Avenue. The turn-of-the-century tenement that Harpo later called (in his memoir Harpo Speaks!) "the first real home I can remember" was populated with European immigrants, mostly artisans--which even included a glass blower.
Context: In January 1910, Harpo joined two of his brothers, Julius (later "Groucho") and Milton (later "Gummo"), to form "The Three Nightingales", later changed to simply "The Marx Brothers". Multiple stories--most unsubstantiated--exist to explain Harpo's evolution as the "silent" character in the brothers' act. In his memoir, Groucho wrote that Harpo simply wasn't very good at memorizing dialogue, and thus was ideal for the role of the "dunce who couldn't speak", a common character in vaudeville acts of the time. Harpo gained his stage name during a card game at the Orpheum Theatre in Galesburg, Illinois. The dealer (Art Fisher) called him "Harpo" because he played the harp. He learned how to hold it properly from a picture of an angel playing a harp that he saw in a five-and-dime. No one in town knew how to play the harp, so Harpo tuned it as best he could, starting with one basic note and tuning it from there. Three years later he found out he had tuned it incorrectly, but he could not have tuned it properly; if he had, the strings would have broken each night. Harpo's method placed much less tension on the strings. Although he played this way for the rest of his life, he did try to learn how to play correctly, and he spent considerable money hiring the best teachers. They spent their time listening to him, fascinated by the way he played. The major exception was Mildred Dilling, a professional harpist who did teach Harpo the proper techniques of the instrument and collaborated with him regularly when he had difficulty with various compositions. In the autobiography Harpo Speaks (1961), he recounts how Chico found him jobs playing piano to accompany silent movies. Unlike Chico, Harpo could play only two songs on the piano, "Waltz Me Around Again, Willie" and "Love Me and the World Is Mine," but he adapted this small repertoire in different tempos to suit the action on the screen. He was also seen playing a portion of Rachmaninoff's "Prelude in C# minor" in A Day at the Races and chords on the piano in A Night at the Opera, in such a way that the piano sounded much like a harp, as a prelude to actually playing the harp in that scene. Harpo had changed his name from Adolph to Arthur by 1911. This was due primarily to his dislike for the name Adolph (as a child, he was routinely called "Ahdie" instead). The name change may have also happened because of the similarity between Harpo's name and Adolph Marks, a prominent show business attorney in Chicago. Urban legends stating that the name change came about during World War I due to anti-German sentiment in the US, or during World War II because of the stigma that Adolf Hitler imposed on the name, are groundless. CANNOTANSWER
Question: Did he go on stage with anyone famous?

Answer:

The major exception was Mildred Dilling, a professional harpist who did teach Harpo the proper techniques