There is a small portion of music in Billy Joel's Vienna, specifically from 2:00 to 2:05 of this clip. It sounds very familiar and I feel I've heard it in another (most likely country) song, which has a lot more repetitions of this piece. Can anyone recognise it?
As far as I can tell, this isn't intended as a quote of a specific piece of music but rather to evoke the street musicians of Vienna. That particular accordion style actually originates as the "Bal Musette" in 1880s Paris, but it's common in Vienna, where it would more typically be in waltz time.
If you notice, the accordion section shares the meter and tempo, and tracks all the the harmonic changes of "Vienna," which suggests it was composed or improvised as a solo for this particular song (but in the Musette style). Typically an interlude like this would be intended to sound intensely familiar, but (hopefully) without being an actual identifiable copy of someone else's song.