The Swiss National Museum in Zurich has been the go-to institution for all things Swiss since its inception at the end of the 19th century. However, when the rich exhibitions hosted in the museum's original 1898 home – designed by architect Gustav Gull – started outgrowing their historic base, a new strategy was needed. Enter Basel-based architects Christ & Gantenbein, who won the competition for an extension in 2002. 

The new wing is unmistakably modern, carving an abstract geometric concrete form against the old structure and the nearby Platzspitz Park. Old and new sit side by side harmoniously, designed so that the visitor experience and movement can be smooth and uninterrupted between the two elements. 

The architects liken the new structure's sculptural shape to a bridge. 'It spans across a wide space', the team explains, 'featuring a water basin [landscaping for which will be completed in May] that connects the new inner courtyard with the park.' 

As disparate as they may sound, the team hastens to add that there are key design similarities between the 19th century building and the raw concrete volume of the new. They both share thick, robust walls – the new wing's are some 80cm thick – to fulfill the area's high thermal insulation requirements. They also feature high quality flooring, with decorative period terrazzo matched by high standard, modern polished concrete. 

Interiors were kept clean and adaptable, to host both traditional and more experimental displays. At the same time, smaller tweaks across both buildings – such as moving the main entrance to the spot where the old meets the new – complete the overall complex's refresh. 

The extension is now finished and the sculptural new addition has just launched officially to the public. And still, this is not the end of the redevelopment of the Zurich institution. The historical west wing and tower will close in 2017 for refurbishment, to reopen completely revamped in 2020. Watch this space.