Rummelsburg has experienced a remarkable surge in the last decade, with hundreds of new homes, the Sisyphos club and the awesome Funkhaus concert and exhibition venue. Close to that building you can also find the Heizkraftwerk, the heating plant.
It has been preserved quite well and the vast central space on the first floor has this authentic, rusty feeling including cranes. It is being used for special events such as festivals and product presentations, it definitely makes sense to keep an eye on them and grab your chance to visit. In summer you can finish that visit with a pizza at the adjacent excellent Casa di Legno.