[jmcdowell]

Any idea who would have "126 million images along with their accompanying Exif location data."?

That seems an insane amount to me.

[cfcef]

Sounds like 'all public Google+ photo albums'. (I say public because given what Facebook reports about daily photo uploads, a cumulative 126m seems like it would be way too small for G+ if it covered all Google Docs/Photos uploads including private ones.)

[michael_h]

Android phones that backup all the photos to Google Photos? Seems like a good place to start.

[nl]

Google Street View

[dooptroop]

Yup. And we've already been tagging locations with adresses for years through that captcha.

[nl]

That isn't exactly needed for this. The GPS location will give you a street address close enough for the metrics used by this.