Constantin

prop. n. the former capital of the Eastern Roman Empire; it was built on the site of ancient Byzantium, and the name was changed to Istanbul by the Turks.
Syn. -- Istanbul, Stambul, Stamboul. [ WordNet 1.5 ]

The name change was the subject of a humorous song in the 1950's "Istanbul (not Constantinople)":

 Artists: The Four Lads -- peak Billboard position # 10 in 1953 -- Words by Jimmy Kennedy and Music by Nat Simon -- (C) Chappell & Co. Istanbul was Constantinople Now it's Istanbul, not Constantinople Been a long time gone, Constantinople Now it's Turkish delight on a moonlit night Every gal in Constantinople Lives in Istanbul, not Constantinople So if you've a date in Constantinople She'll be waiting in Istanbul Even old New York Was once New Amsterdam Why they changed it I can't say People just liked it better that way Take me back to Constantinople No, you can't go back to Constantinople Now it's Istanbul, not Constantinople Why did Constantinople get the works? That's nobody's business but the Turks'