"Perspex" Perspective

I was in the city for a flying visit today. Had a variety of fiddly things to chase up. The Hilton Hotel in Sydney has this huge glass canopy over the driveway outside the main foyer. At first I thought it must be perplex because the suspension system didn't seem heavy enough to support glass. In any event I thought the visual tricks that the canopy performed with light made it a worthwhile blip. (amended text)