Beautiful architecture most often consists of arresting forms that please and animate the viewer, even as they provide essential functionality. Just as often, the enabler of such structures is steel, the only material that can deliver the requisite strength-to-weight ratio these shapes demand.

A recent example is “Schutterstoren,” an award-winning, cylindrical apartment building in western Amsterdam’s newly renovated Westelijke Tuinsteden residential district. Elevated 6.5 metres above ground level, the 13-storey apartment block features dramatic cantilevers that extend from a narrow cylinder-shaped concrete core. From this height and above, the large overhang offers sweeping views of the adjacent lake, Sloterplas, while providing great flexibility in the size and configuration of individual apartment units.

One of numerous new apartment blocks in the district, Schutterstoren is unique in its circular shape, which functions as a visual focal point, bringing cohesion to the scatter of surrounding buildings. While the zoning plan imposed height restrictions, the building’s exceptional appearance validates its role as the district’s landmark. Stunning enough during daylight, at night the building is illuminated from below, creating an appearance of floating above the landscape.

With this type of building, minimizing overall weight was crucial, so the Rotterdam architectural firm DKV architecten relied on a main supporting structure of steel columns and beams, with the concrete core at the centre. The columns stand back slightly from the façade to reduce the overhang and keep the façade structurally independent. Diagonal tie-rods on the two lower floors transfer forces from the overhang to the core, enabling conventional stacking of the remaining 11 storeys above.

The small plot selected for the tower limited the size of the car park. Making virtue of necessity, a greensward mound beneath the building conceals a 78-place circular garage around the concrete core and creates a park-like landscape.

The basic design, employing steel, enables free and flexible apartment layouts on the 10 standard storeys. Storeys one and two are exceptions, where the diagonal tie-rods are somewhat restrictive, as is the top floor, where patio-like loggias limit options.

Lifts and staircases are in the concrete core. Surrounding the core are communal access points and, moving outward, the shafts containing pipes and ducts. Between the shafts are recesses for apartment entrances and just outboard are individual apartment service areas. Out from these to the façade is open space, offering unfettered latitude for design of apartment size and layout. Steel studs provide the framework for partitions.

The apartment block’s circular, open design allows as many as six units per floor or just a single apartment taking an entire storey. No two apartments are the same. As future residents intensively followed construction progress, they gained insights about the spatial attributes of the rounded form and imagined their own layouts. The use of steel enabled them, also, to evolve their thinking until uncommonly late in the construction process.

Schutterstoren is winner of the 2008 Amsterdam New Estate Prize as it was chosen by Amsterdam residents as the best residential project of 2008. In 2004 it was nominated for the Nico Nijmeijerprice Amsterdam for the most dynamic development project.