The conversion of the large former Toni milk processing plant into a location for education, culture and housing creates a link between two very topical developments. On the one hand it establishes a new focus of educational facilities within the landscape of third level education institutions in Switzerland, which has been massively remodelled over the last few years. On the other hand, for some time now Zurich’s District 5 has been undergoing a transformation process that is changing it from a monofunctional industrial quarter into an urban district with mixed functions. This process is also altering the character of the city as a whole and leaving its stamp on it. The intention of the commissioned study was to find a concept for a building that is almost the size of an entire urban block. The aim was to enable the productive coexistence of a wide variety of functions within the project, while at the same time introducing creative impulses that exert a positive effect on the adjoinin urban space. We believed that this task was not primarily an architectural one but primarily an urban planning and program-related question. Our design responded to the size of the project by using a kind of internal urbanism. The existing system of ramps was reinterpreted as a vertical boulevard and became the building’s main circulation system. As a counterpart to this, we placed the large entrance hall conceived as a public space at the intersection of the high-rise and the lower building. An internal spatial figure connected by a sequence of halls, squares, voids and cascading staircases was created that positions the many different functions like buildings in a city and is a spatial catalyst that makes internal exchange possible. Through its variety of functions the building has an external impact, becoming the central public place of a new urban district. The generously dimensioned roof garden gives the district back a piece of outdoor space. At the architectural level the project raised a number of questions, for instance how to deal in design terms with the very divergent scales or with highly specific functions, or what might be the appropriate atmospheric mood for this extremely dense complex. In this regard the existing industrial building offered a kind of productive resistance that made it into our sparring partner. Its performative and spatial qualities live on in the new building, directly and indirectly, starting with the sculptural form of the building and its expanded metal facade – an interpretation of the original trapezoid profile sheet metal facade – and extending to the concrete plinth that develops the topography of the former deliveries area, and to the formative sequences of spaces inside the building. The industrial character of the interior with its exposed services is fed from the world of images of the old milk processing plant. The use of raw, direct materials in the interiors is not an aesthetic end in itself, but creates an open framework for the activities of students and lecturers. The Toni Areal is intended to be an approachable building, which can deal in a pragmatic way with the pressure of constant change that a lively university campus exerts on its spaces. Appropriation, change and exchange are expressly called for. To produce variety and diversity the architecture works with grades of refinement that differ from place to place: generally raw, here and there more refined, sometimes overelaborated but mostly under-defined. A wide range of extremely different spaces is created that includes functional public halls and circulation spaces as well as intimate practice rooms, a multifunctional workshop and a highly specialised sound studio: the building as city, the city as building.