Google Street View is quite useful when you need to get a sense of place, but now you'll be able to get a sense of place and time: Starting today, Google Street View is formally offering users the chance to travel back in time to see how a location has changed, thanks to images dating all they way back to... 2007. For you millennials in the audience, that was the year of the Great Midtown Steam Explosion (you probably won't find it on Google Street View).
If you spot a clock icon under an image in Street View, you'll be able to toggle back in time to the happy, free-love days of 2007 (and you won't have to dig back into the cache, the way some very enterprising folks have). Some NYC time travel locations include One World Trade Center, the ever-changing Bowery mural's graffiti and 5 Pointz—it'll be depressing to see the 5 Pointz update!
Google calls this its "ongoing effort to create a digital mirror"—or "digital time capsule"—"and true record of the world."