Bad Mergentheim is on the main rail line between Würzburg and Lauda, with regular services from both directions. From Würzburg (where most visitors on the Romantic Road begin or end their journey), the train takes about 45 minutes. There are also connections via Stuttgart, changing at Lauda.
By road, the town sits on the B19, which is the main Romantic Road route through this stretch. It is about 35 kilometres north of Rothenburg ob der Tauber and 50 kilometres south of Würzburg — a logical stop on a north-south drive along the route. There is adequate car parking near the castle and in the town centre.