Their distinctive skeletal structure consists of ellipse-shaped steel columns that support a spinelike element running parallel to the edge of the platforms. Angled steel ribs spring upward from the spine and support glass panes that cover the platforms. None of the elements curves, but their varied lengths and angles create the illusion that the canopy curves both from top to bottom and from side to side. Architects and artists call this sort of thing trompe l'oeil, which literally means "fool the eye." LEDs at the tips of the ribs accentuate the curvature.