Location of Rav Hirsch's grave

Jewish Cemetery of Frankfurt, in the Austritt Gemeinde section, Section E. 

Rat-Beil-Straße 10, Frankfurt, near the Frankfurt University of Applied Sciences

Nearest train stop: Frankfurt (Main) Münzenberger Straße, 18, light rail

Nearest bus stop: Bus stop Frankfurt (Main) Richard-Wagner-Straße, M32

This is not the Old Jewish Cemetery that's near the Jewish museum near the Main river. "The Jewish Museum Frankfurt is located in the city center, next to the old Jewish cemetery, which is the oldest surviving Jewish cemetery in Frankfurt and dates back to the 13th century." It's not that one. 

This is the general look of the place. 

Jewish Community Frankfurt - Cemetery Administration

Phone: +49-69 / 76 80 36-790

E-mail: friedhof@jg-ffm.de

The cemetery is locked at night. Gate is opened for free access at 10 AM. 

Portal:

Second entrance. You enter here.

Third gate is locked:

Wall is around eight feet high. 

Enter the middle gate -- Eingange -- make a right and walk along brick wall for around 80 meters. Walk until you reach another brick wall. Step through the opening in the wall. 

On the right you will see another metal gate, what I am calling the third gate. Turn left and go around 50 meters. Grave will be to your right. 

Good news for Kohanim. You can see the tombstone by peering through the opening in the third gate. Peering through the gap in the gate. Arrow points to the grave. 

There are overhanging trees along part of the wall, but not at the third gate. You might need someone to point it out to you though, someone who is inside the cemetery. 

https://alemannia-judaica.de/frankfurt_friedhof_rat-beil-strasse.htm

https://de.wikipedia.org/wiki/Alter_j%C3%BCdischer_Friedhof_Rat-Beil-Stra%C3%9Fe