The “Lyoner Viertel” in Niederrad, Frankfurt is undergoing major change. An ever increasing amount of empty office space prompted a plan to convert it for residential use, thereby helping to regenerate this part of town. Leading the way in this initiative is the transformation of an empty office tower from the late 1960s into a residential block with 98 apartments. The simple cubic shape of the existing building was extended upwards by three storeys (including the top floor set back from the façade), the parapets were lowered and on the corners of the building loggias were created. Now more elegantly proportioned, the outward appearance with its strips of windows above white parapets, reminiscent of the classical Modern, and the clearly modelled ground floor, signals the functional changes within. Thanks to the square plan and the space between the two lifts, the core of the building could be used for sanitation installations and for other infrastructure. Flexible ground plans allow for an interior arrangement with two to seven apartments leading off each hallway.