About 1.5 hours south of FRA is one of the best aviation and auto museums I've ever seen. They have a rare collection of displays including the Russian SST (TU-144) and Concorde mounted in take off configurations. You actually get to climb up into these aircraft and the only place inthe world displaying both and the only TU-144 outside of Russia. Highly recommend visiting and have a short video and directions how to get there (at end of video) if interested.