Up until now, the concept of "augmented reality" was a futuristic take on the here and now: your smartphone would grab your location and give you up-to-date info on where to eat, shop, sightsee, or grab some mass transit. But what if you could see what the streetcorner you're on now looked like, oh, a century ago?
That's the idea behind Museum of London: Streetmuseum, an iDevice AR app that packs over four hundred years of history ("from the Great Fire of 1666 to the swinging sixties," as per the App Store copy) into your handheld device. Use the app's built-in map or your GPS to locate a point of historical interest, like so:
Once you've arrived, hold the camera up — and the present-day scene is overlaid with images from its past incarnation(s):
And a quick tap of the screen brings up a page of historical facts:
The app even takes into account London's ever-changing topology, offering landmark hints to pin down a particular location. Best of all, it's free — so you can save your Euros for important things, like those import-only Black Sabbath reissue CD's.