With the car: 

Via A 5:
Coming from south or north till Nordwestkreuz.

Then change to A66 Frankfurt Stadtmitte – Miquelallee.

At the lighting you go right to Hansaallee.

You stay on the right lane and go right at the second lighting.
Now you keep straight on and after the first lighting you are
in Reuterweg. Within the next 500m our office is on the
left handside.