This Master Thesis concerns the design of a comprehensive extension to an existing museum of fine arts, located in Mänttä, Finland. The project is based on a competition brief by Gösta Serlachius Fine Arts Foundation, completed in 2011. The report is a presentation of tectonic studies followed by a final building design and a design process that becomes a media for discussion with departing point in our tectonic extractions. The thesis intends to explore the linkage between poetry and construct in our reach for architecture that moves people beyond practicality. An poetic key role of architecture is found as the mediator of culture, entailing a focus on architecture’s mediation of representatives of culture; man, place and art. A tectonic approach of staging as a spatial gesture becomes the linkage that mediates man, place and art in construct through the potential of staging in a structural principle.