Untitled (1964) is a crystalline form made of steel and mirrored plastic, which reflects all the surfaces of the surrounding architecture and reflecting itself within its illusionistic interior. In a related drawing from 1964 titled Three Works in Metal and Plastic, Smithson notes that with this sculpture creates a "Double vanishing point—exists as a solid reversal of traditional illusionistic perspective.

Robert Smithson’s Mirage No. 1 is an arrangement of nine framed mirrors that increase in size from one square foot to one square yard. Hung low on the wall at regular intervals, the mirrors create an experience of displacement: as they reflect the movements of people in the gallery, the shifts in the mirrors’ sizes cause jumps in scale, and the gaps between them interrupt visual continuity.