Fifth Third Bank doesn't operate in Fort Wayne, but it has a very visible presence in this part of the country, including Indianapolis. Every time I visit my mother and sister there, I see a Fifth Third branch and wonder where in the world the name came from. I've asked around from time to time, and the answer is usually something like "those are the streets the bank started on in Cincinnati." I finally looked it up, and the real answer is even more mundane, but interesting in its own way, as Cecil Adams points out.
UPDATE: Oops (see Dave's comment). Guess I should get out north more. UPDATE to the UPDATE: John chimes in.