This narrow townhouse with an extraordinarily deep rear yard offered the owners the chance to have an urban home with indoor/outdoor living. The clients wanted the garden to become another room. And, they were committed to a modern aesthetic. We looked at modernist architectural history for inspiration, and drew from the steel structure used in Case Study housing to provide the answer. The back wall of the townhouse was removed at the ground and first floors, and a steel frame was inserted. The structure activates the first floor’s living and kitchen areas through the back wall, and frames the picturesque garden moment. In a series of glass door panels that open in an accordion fold, the boundary is erased, creating a seamless transition from inside to outside. The basement level of the extension provides his-and-hers hobby rooms. His pottery studio and her quiet reading room exist side-by-side, each with a view and access to the garden.