Frankfurt has a rep as the most "american" city in Germany. Itīs the finance headquarter of Germany, but also the city with the highest crime rate, it depends on where exactly you want to spend your time. You should be safe in the inner city districts, but I wouldnīt suggest the surrounding suburbs. Itīs in the state of Hesse, which is famous for their "Eppelwoi" (Applewine). There arenīt many culinary specialties I could suggest, aside from the typical sausages.
To be honest, Frankfurt wouldnīt be my first choice as a tourist, itīs a rather ordinary city. If youīve got some time to spend, I suggest you visit some of the more rural areas of Hesse, as the landscape is quite beautiful there.