The first CAVE was designed by Carolina Cruz-Neira, together with Tom DeFanti and Dan Sandin, at the University of Illinois at Chicago in 1992, and presented at SIGGRAPH the same year. The term is a recursive acronym for "CAVE Automatic Virtual Environment" as well as a reference to Plato's Allegory of the Cave, which considers the idea of reality as rendered illusion. Since 1992, similar facilities have been constructed at various sites around the world; the fact that these sites represent both academic and commercial interests suggests that VR is extending beyond research labs and science fiction into the real world. While most of these CAVE-like facilities (including those at Chicago and at UCL) consist of 4 walls, there are some that have 6 projection surfaces (4 walls, floor & ceiling) completely enclosing the user in virtual space.