This article is from the German Genealogy FAQ, by Jim Eggert EggertJ@crosswinds.net with numerous contributions by others.
Assuming that the family name is a place name perhaps with the
common suffix -er (as in Oberheimer), then it is very possible that
the family did indeed come from that place (Oberheim) originally.
But they probably left that place before they acquired the surname,
which was probably before the earliest extant records, so you will
likely never be able to prove it. Also note that place names are
often shared by several towns, and that a surname may be related
etymologically but not genealogically to a place name.
 
Continue to: