What happens when you take 200 Lumia 820s and pin them to a wall? You get a 12,000 x 6,400-pixel display, natch. This week at Build 2013 in San Francisco, Nokia and Microsoft teamed up to show this tiled monitor made of identical phones each running the same custom-built app. A master handset is used to control what's on the wall by communicating with each phone over WiFi (IP multicast). One demo was showing a massive animated grid of live tiles representing a selection of apps from the Windows Phone store. In another demo, the wall was displaying Bing Maps (using Here data) and being controlled interactively by the master handset. Take a look at our gallery below.