Benthem Crouwel Architects • Amsterdam, the Netherlands

The "bathtub" addition to the Stedelijk Museum, in Amsterdam, the Netherlands, has been completed. Photo: John Lewis Marshall

The recently completed Stedelijk Museum in Amsterdam, the Netherlands opens to the public on September 23. Amsterdam-based Benthem Crouwel Architects designed the project, including the renovation of the museum's 1895 brick building, and the new addition, nicknamed "The Bathtub" for its form and sleek white facade, currently being assembled.

The addition essentially consists of a large canopy extending out about 40 meters (130 feet) at the roof level of the existing building, with a smooth white volume descending from the roof that narrows as it nears the glazed ground-floor base. Galleries, a new auditorium, and various other spaces are divided between this volume and an underground portion of the addition, while the transparent ground-level volume houses the museum shop and restaurant and the new entrance to the facility.

The museum addition abuts the existing historic museum building. Photo: John Lewis Marshall

The facade consists of a surface about 2,800 square meters (30,000 square feet) in area, made up of 271 composite panels attached to the steel structure, giving the appearance of seamlessness. The panels combine aramid and carbon fibers from Japanese manufacturer Teijin with vinylester resin and PIR foam core.

While presenting a stark contrast to the historic museum building, the addition also steps lightly on its site, preserving sightlines to the existing brick facade and defining an entrance plaza facing the Museum Square (Museumplein). The expanded museum now boasts around 8,000 square meters (8,600 square feet) of exhibit space.

Queen Beatrix of the Netherlands will preside over the building's opening ceremony on September 22.

The cantilevered roof of the Stedelijk Museum addition.  Photo: John Lewis Marshall

A bridge between the new and old portions of the Stedelijk Museum. Photo: John Lewis Marshall