Type "77 Massachusetts Avenue 02139" into Google Earth, and you'll see MIT's Great Dome in all its glory. Click a button to zoom out, and soon you'll see the state capitol, the celebrated Zakim Bridge, and maybe some other college up the river. (Watch a video demonstration.) These images, which are shared by Google Maps, are actually a combination of aerial photos and satellite ­imagery--and a lot of post­processing. Technology Review interviewed engineers at Google and at ­DigitalGlobe, the company that supplies Google's satellite photos, and did a little bit of reverse-engineering to figure out how it works.

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