...from Berlin Hauptbahnhof:
Bus 240 heading to Storkower Straße, 6 stops, get off at Rosenthaler Platz.
Duration: 12 minutes (10 by taxi)

...from Tegel (TXL):
Bus 128 heading U Osloer Straße, 15 stops to Osloer Str. Change to U-Bahn U8, heading to S+U Hermannstraße, 7 stops to Rosenthaler Platz.
Duration: 37 Minutes (20-25 minutes by taxi)

...from Schönefeld (SXF):
5 Min. by foot to S-Bhf. Flughafen Schönefeld; Regional Express trains heading to Nauen, 3 stops tp S+U Alexanderplatz. Change to U-Bahn U8 heading to S+U Wittenau, 2 stops to Rosenthaler Platz)
Duration: 35 minutes (45-60 minutes by taxi)