Koh uses two-dimensional photography to create holographic, three-dimensional constructions. His photo sculpture has a transparent surface that reflects the images of the world, and yet reveals the emptiness of its interior space. The overlapping planes create an illusion of indefinable depth and varying imagery, depending on the viewing angle. Building-57 is a circular, building-shaped work that mixes two different spatial images. Photographic images of the interior of the Metropolitan Museum in New York and the British Museum in London are collaged together to depict its exterior.