Bad Mergentheim is currently a small resort town centered around a famous spa featuring water from the local mineral springs.
From 1525 to 1809 Bad Mergentheim was, as you probably know, the headquarters of the Teutonic Knights. The old Teutonic Knights headquarters takes up the greater part of the downtown area.
The main castle of the headquarters now serves as a museum.
The church connected to the castle was designed by the ubiquitous Balthazar Neumann, who also built the Residenz and the Kappele in Wurzburg.