Check out Saalburg Roman Castle and Archeology Park and find out about its role in defending the area. This structure has witnessed some interesting history during its time.
You'll have no end of sightseeing choices in Bad Homburg v.d. Hoehe. Saalburg Roman Castle and Archeology Park is a good place to begin here, but there are many other worthwhile attractions to discover. Taunus Therme, Hessenpark, and Kurpark are not far from the history-filled fortress and and will cap off your day nicely.