Concrete spiral staircase twists through open-plan office by Hildebrand

A spiral staircase made of concrete rises through the centre of an open-plan office designed by architecture studio Hildebrand in Steinhausen, Switzerland.
Winding its way up the building's four levels, the staircase ends with a large elliptical skylight that brings light into the centre of each floor.
Photo is by Erica Overmeer
Hildebrand designed the headquarters for Hapimag, a Swiss holiday company. As well as providing access, this stairway was designed to double as an informal gathering spa