The Inside Story

Firm: Behnisch Architekten

Site: Hamburg, Germany

Built in 1841, the Handelskammer Hamburg in Germany is about as neo-Renaissance as a building can get. Which meant, as any architect today knows, that altering it was nigh on impossible—not, anyway, without convincing a landmarks commission concerned about the corruption of the building's purity of line and proportion and risking the ire of a community grown fond of a 167-year-old silhouette. So how to address the chamber of commerce's need for over 10,000 additional square feet of office, conference, and public space?

Behnisch Architekten proposed the bold idea of erecting a virtually freestanding structure—essentially three stacked boxes of polished stainless steel and transparent or translucent glass—inside the building's courtyard, which had already been roofed over. On top of the considerable technical challenges facing partners Stefan Behnisch and Martin Haas was a request, issued by chamber members, that construction would progress in such a way that business as usual could continue. "We had to prefabricate and assemble most of the elements off-site and deliver them as discreetly as possible," Haas says.

Reached by catwalks on two stories, Haus im Haus—as it's been nicknamed—not only serves its business-related functions but also provokes a reassessment of contemporary and traditional architecture.

From left: Catwalks provide access to the new structure from the 1841 Handelskammer Hamburg. Antonio Citterio designed the chairs in the private dining room. LED panels light up the stainless steel structural grids that form the floor of the structure's topmost volume.

Opposite: The open dining area sits on top of the volume housing a permanent exhibition of the organization's history.

From left: The steps are plaster-covered folded steel. Flooring on the first level is steel-reinforced glass.

FROM FRONT MOROSO: CHAIRS (DINING ROOM). MDF ITALIA: TABLES (DINING ROOM, AREA). POLTRONA FRAU: CHAIRS (DINING AREA). THROUGHOUT NIMBUS DESIGN: LED PANELS. ULRIKE BRANDI LICHT: LIGHTING CONSULTANT. WETZEL & V. SEHT: STRUCTURAL ENGINEER. TPLAN: MEP. THEOURBACH: CONCRETE CONTRACTOR. ALOIS BAUMANN: CURTAIN WALL CONTRACTOR.