by car, your trip from the frankfurt airport to rothenburg is 112 miles/under 2 hours traveling time with its own exit off of the A7 autobahn. there is a MAJOR train station at the airport, but i'm not sure if you would have to go to the main train station in frankfurt. from my research, rothenburg is the terminus of a branch rail line from steinach via wurzburg. the german national railroad (deutsche bahn) has an excellent web site that will be able to give you specific information.

barry in new jersey