As an extension to the main building of CAUP(college of architecture and urban planning), Building C is programmed for research and graduate student education on a congested site, with main building adjoining western side and campus enclosing wall next to northern side. The appearance of this building is considered as revelation of dormant potential of this silent corner in the campus, which intends to re-establish its relationship with the campus, the main building and the city. This is a building encouraging sufficient communication and inspiring hidden enthusiasm and creative instinct beyond rational system, so that the process of using it is also the revelation of dormant potential for users themselves. The space is envisioned as a kind of flowing continuum and the numerical relationship between service and serviced space is broken through, so that the communication space becomes the main component, and the functional space as plug and play element. The core of building C is a centered east to west connecting corridor system, including a straight staircase connecting all floors of working space and a series of vertical light shafts. Sufficient daylight and diffuse space create a communication place for all professors and students. Research workshops, as the main body of the building, cover all the upper floors on the south of the corridor. Supervisors studios / flexible workshops and vertical circulation / service units are arranged as two volumes plugged in different heights on the north of the corridor, with three overlapping voids in between (two indoor planted atriums on basement and third level, and a roof garden on seventh level). They share a common transparent glass envelop on the north facade. Waterfall and stepped plant incorporated into the sunken garden to the south provide a vivid recreational space to the underground gallery. The overlapping of large scale public space from north to south produces intense variation in space dimension and orientation, and intertwines inside with outside. The building becomes the filter of the whole environment. In order to interact with environment and demonstrate its interior mechanism, we try to seek the visibility of interior space and the expressivity of surface material instead of the unity of exterior facade. Different space types have been distinguished in forms and materials of the facade, making each surface of the building respond to different context of the site.