Füssen, Füßen... Ah, I didn't know that I could post non-English characters on this site. I absolutely avoid doing it in emails. The umlaut (the two dots) is usually respelled as an added "E" (Ä=AE and Ü=UE) in domain names and such to make it universally recognizable in digital form. The eszett (ß) is somewhat interchangeable with "ss", but there are specific rules. I don't know them, but "Füssen" seems never to be spelled "Füßen".
I suppose this arcane knowledge is not useful to the OP, but it's kind of fun for linguistics nerds
