Rosenthalerstrasse 72a | Mitte with two other branches in Helmholtz Platz and Zehdenicker.
Sunday to Monday from 8am to 12midnight
Friday and Saturday from 8am to 3am
St Oberholz is the Mecca of the freelancers and co-workers in Berlin. Not only a great spot for a coffee and sandwich but to network while connected to their wi-fi. It is (almost) always open so you can have breakfast, work and stay for happy hour. Their Facebook page is full of nice events and info on co-working in Berlin.