Do you have an original record with the name written out, or is that family tradition? I couldn't find any places called Mundorf, though Mundorf is a surname.
Here are possibilities...
Münzdorf in Hayingen, Reutlingen, Baden-Württemberg
Münnerstadt in Bad Kinssingen, Bavaria ("Dorf" means village while "Stadt" means city)
Mindersdorf in Hohenfels, Konstanz, Baden-Württemberg
Mondorf, in Niederkassel, Nordrhein-Westfalen
Mondorf in Merzig, Merzig-Wadern, Saarland
Müngersdorf in Köln, Nordrhein-Westfalen