Limoncello was first made on Italy's Amalfi coast, with several different villages and islands claiming it as their own, from Sorrento to Capri.
Some say a citrus-grove tender from Azzurra passed along her recipe to her bartender nephew at the turn of the 19th century, and that it came to be customarily served as a special treat to guests by the wealthy families of Sorrento.
Others say limoncello dates back much further, invented either by monks (as was Chartreuse, in France) or fishermen who took a shot to ward off the cold. The name was trademarked by Naples businessman Massimo Canale in 1988.
Good luck, Massimo. At this point in limoncello's popularity, that's like trying to trademark the word "lemon."