Small club but very good, high-end equipment inside. €25E admission fee is steep, especially if you're exchanging currency for calories. Some hotels in the area receive guest discounts, so use your persuasion skills to save 50%. They have vouchers available on their website, so if you're not the bargaining type, give the free online pass a try.
A wide selection of the typical high-quality cardiovascular and resistance training equipment, as well as a "freestyle" training area for some more bodyweight-focused routines.
The club is located in the upper part of the MyZeil shopping center, easily accessible via the stops Konstablerwache and the main station.