Frankfurt has a Jewish history dating back to at least the 12th century and there is some excellent information on the web to guide you to key cultural sites within Frankfurt, http://en.juedisches-frankfurt.de/
There are two museums in Frankfurt city centre dedicated to Jewish heritage in the city, both offering extensive information in English as well as German. Be aware however, the the Jewish Museum (opposite the river on Untermainkai 14) is closed until 2018 for renovations. The museum of the Jewish Ghetto is open, and newly renovated, and includes as a permanent exhibit the original foundation stones of the ghetto from 1462. In addition to these two central museums, is the Bildungsstätte Anne Frank, a small exhibit dedicated to Anne Frank, whose family lived in Frankfurt until the National Socialist regime forced them to move to Amsterdam. This museum is easily accessible by taking the U-bahn (1,2,3 or 8) to Dornbusch. During my last visit they were exhibiting the original diary of Anne Frank.
As well as the information listed on web about Frankfurt Jewish culture there are some additional places to visit which have a Jewish connection. Up near the old opera house is the Rothschildpark, situated on land where the Rothschild's once lived. A placard by the park entrance, on Bockenheimer Landstraße, offers information and photos about the family home that once stood there.
Not far from Konstablerwache is a remnant of the old city wall, the Staufenmauer, dating back to the 12th century. It's also the north entrance to what used to be the Jewish ghetto, first constructed in 1462 and, up until 1815, Jewish residents were confined to living there. Today nothing exists of the old ghetto but walk through the old north entrance and head south towards the Jewish ghetto museum (Museum Judengasse) and you will be treading the path of where the ghetto used to stand.
As you reach the Jewish ghetto museum, on the south east corner of Kurt-Schumacher-Straße and Battonstraße, look out for some brass plates laid into the ground with house names on them, e.g. Goldenes Schaf. The brass plates outline where some of the ghetto houses previously stood and are part of the museum exhibit. The entrance to the Jewish ghetto museum is 30 metres along Battonstraße and it is the ideal place to visit for more information about life in the ghetto.
Next door to the museum, is the old Jewish cemetery, in use from the 1200's through to the 1800's. Around the cemetery walls are listed almost 12,000 names, the names of the Jewish Frankfurt citizens murdered during the holocaust. Follow the wall to the south side and into the Neue Borne Platz, previously the old Jewish market place, today it is a permanent place of remembrance. If you wish to enter the cemetery a key can beborrowed from the museum, but only on production of a valid ID card.
This link also gives details of the other two Jewish cemeteries in Frankfurt, which are both accessible via a short ride on the U-bahn.
In the heart of the old town, on Römerberg stands the Alte Nikolaikirche. Step inside and notice the colourful stained glass windows in the south wall and one to the west. These windows formerly belonged to Carl von Weinberg. Born into a Jewish family, in the 1880's he converted to the evangelical faith however, because of his Jewish beginnings, the National Socialist regime reclassified Carl von Weinberg and forced him to sell his estate. The window's creator, Lena von Schauroth, took the windows for save keeping and in 1951 permission was given for the windows to be installed in the Alte Nikolaikirche. Another relic from the von Weinberg estate is the Florentine fountain, an original 16th century renaissance sculpture which can be found in the Wallanlage park, next to the Nebbiensches Gartenhaus.
The Goethe University grounds in the Westend, house the Wollheim memorial, dedicated to slave labourers forced to work at IG Farben during the second world war. The main university building is the former IG Farben headquarters. The public are free to walk around the university grounds which connect up with the Grüneburgpark, and the Botanical Gardens.