That the Berghain used to be a real, functioning heat plant, can best be seen in the adjacent Kantine. In the main room there is a beautiful wall painting of the big building, including the (by now vanished) chimneys.
In contrast to the temple of techno, the Kantine is more known for its live concerts. Many of them are electronic acts, but lots of rock bands perform on the small stage as well. Great place, beautiful interior, perfect in even the smallest details, exactly as you would expect it from the owners of the Berghain.