The Stadskantoor's innovative structural system generates maximum efficiency and versatility both in construction and in program: units can be added or even dismounted from the structure as demands on the building change over time, and can adapt to either office space or residential parameters as desired. Green terraces on higher levels provide the possibility of an apartment with a garden in the heart of urban Rotterdam. On the street level, the structure allows for generous open space, with modules overhanging rather than encroaching into an interstitial area, encouraging an active and open engagement between the Stadskantoor and the city.

The design brief stipulated that the Stadskantoor must be the most sustainable building in the Netherlands. OMA tackled this imperative through the building's core concept of flexibility, and also through the two large atriums, which act like lungs. They are connected to a climate system that stores warmth in summer and cold in winter and releases this energy as warm or cold air as required. The building's glass facade uses hi-tech translucent insulation that allows for unprecedented energy efficiency.

Rather than being yet another statement in Rotterdam's crowded history of revisionist planning and cacophony of architectural styles, the ambiguous mass of the Stadskantoor tries to mediate between the existing buildings surrounding it. The axis between the existing town hall and the post office coincides with the axis of symmetry of the Stadskantoor, and the street between these two buildings continues into a passageway to the Haagseveer. The Stadskantoor integrates with the neighbouring Stadtimmerhuis by maintaining the same floor heights, while the plinth height of 20m conforms to the character of the surrounding Laurenskwartier.

Statement by Rem Koolhaas

What does Rotterdam really need?
After an impressive sequence of abrupt architectural transitions - from the stark modernity of the reconstruction, via the "new humanism" of the cubes, the repressed postmodern of the 90s to the current apotheosis of Dutch modernity - launched by the fireworks of the 1940 bombardment, all these ideologies coexist and interact in harsh juxtaposition, each successive layer oblivious and in contradiction to the previous ones.

What is now needed may be subtlety and ambiguity in the midst of an overdose of form. We propose a "formless" heap, consisting of smaller elements that are shaped to perform a number of major and minor responsibilities.

Where necessary the shape can be formal and impressive, almost symmetrical - for instance, from the Coolsingel, glimpsed between the two survivors - and where desired, it can be delicate and accommodating - for instance in its relationship with the existing monument, Stadstimmerhuis.

Our structural system - a three dimensional Vierendeel structure in steel - enables us to improvise and to liberate the ground almost in its entirety, to interpret the "Stadswinkel" as an unencumbered public space, in which we arrange the interaction between citizen and city in a dignified, spacious urban landscape, with an almost "Roman" scale and materiality.