The latest commission in The Unilever Series, How It Is by Polish artist Miroslaw Balka, is a giant grey steel structure holding a vast dark chamber, which in its construction reflects the surrounding architecture of Tate Modern – almost as if the interior space of the Turbine Hall has been turned inside out. Hovering somewhere between sculpture and architecture, it sits on two-metre stilts and stands thirteen metres high and thirty metres long. Visitors can walk underneath it, listening to the echoing sound of footsteps on steel above, or enter via a ramp into its pitch-black interior. How It Is alludes to recent Polish history – for example, the ramp at the entrance to the Ghetto in Warsaw, or the trucks which took Jews away to the camps of Treblinka or Auschwitz. By entering the dark space, visitors place considerable trust in the organisation, something akin to the risks often taken by immigrants travelling. Balka intends to provide an experience for visitors which is both personal and collective, creating a range of sensory and emotional experiences through sound, contrasting light and shade, individual experience and awareness of others, perhaps provoking feelings of apprehension, excitement or intrigue.