Earlier this week I blogged about my interest in combining GPS and city history. A colleague recently sent me a link to a project launched by the Powerhouse, Sydney’s museum of science and design. Today I had a chance to sit down and explore. It uses Layar, an augmented reality tool. If you’re saying to yourself, “Hunh?” then here’s what it means. If you have an IPhone or an Android phone, Layar registers your location and will pull up GPS-encoded information—for example, the closest café, any public events currently taking place, nearby “Tweeters”—as you walk around. In other words it augments your experience of a real place. The Powerhouse has loaded historic photographs of Sydney into Layar. The photos are geo-tagged with coordinates as close as possible to the photographer’s original viewpoint. That means you can pull out your phone in the central business district and pull up what Sydney would have looked like from that same spot in, say, 1926. Layar is still a relatively new tool for museums. The Stedelijk, Amsterdam’s contemporary art museum, offers a Layar opportunity for users to design their own public art and install it virtually on the streets of the city. And two developers in Germany have created a virtual version of the Berlin Wall, where the real wall used to stand, raising all sorts of implications for city museums (imagine using Layar to remake all our bulldozed landmarks). Other museums are using different augmented reality tools besides Layar within the bricks-and-mortar exhibition space (examples include the “Mobile Augmented Reality Quest,” the Allard Pierson Museum, and the Louvre). This is interesting stuff. I caution that technology for technology’s sake is never a good idea. And it’s going to take years for the small museums to get around to such projects—they’re still struggling to pay the electricity bill. But let’s at least spend a little time dreaming about the possibilities. For example, historic sites face significant physical challenges because proper preservation requires so many restrictions. Why not use augmented reality to recreate for visitors what a particular historic space looked like, without having to make any real changes to walls, floors, and furnishings? Or why not have residents create their own mental maps in Layar of their most important urban places? And speaking of layered history, with an e this time, why not use augmented reality to show a street corner in Sydney not just in 1926, but from prehistory up through present day? The past is present, indeed.