Cities change so much that, paradoxically, we may fail to notice. Even big changes can creep up on us so gradually — or fade in our memories so swiftly — that we soon take them for granted. If you could step back a year or five or more on San Francisco's streets, what might you see with that you've since forgotten?

Brazilian urban design group Urb-i had such a question in mind when they launched a before-and-after photo archive of great cities around the world last year, asking users to chronicle the metamorphosis of their city's streets via Google Street View's handy Time Machine function.

Today, Urb-i has over 1,000 images of 28 cities, so you can see once-neglected corners of Tel Aviv, Paris, Buenos Aires, and of course San Francisco turn from asphalt dumps into pretty, walkable, bike-friendly avenues.

Check out some of the city's most significant presto-chango acts from the last 10 years below. And if you know a good spot that's not in the gallery yet, consider digging up some archived images and contributing to the cause.

(Images, in order: 1. Annie Street; 2. Beale Street; 3. Ocean Avenue; 4. Clementina Street; 5. San Jose Avenue; 6. Jefferson Street; 7 & 8. Castro & Market; 9. Naples Street; 10. Mason Street; 11. Howard Street; 12. Cesar Chavez; 13. Post Street)



