Karlstadt is a town in the Main-Spessart in the Regierungsbezirk of Lower Franconia in Bavaria, Germany. It is the administrative centre of Main-Spessart, and has a population of around 15,000.
Wikipedia https://en.wikipedia.org/wiki/Karlstadt_am_Main
Coordinates 49°57'42.056" N 9°45'55.843" E