Shawn Clover is a San Fran resident who's used old photos from the aftermath of the 1906 San Francisco earthquake and mashed them up with photos he's taken from the exact same spot over 100 years later.

The photos are stunning: 

http://shawnclover.com/2010/10/01/1906-2010-the-quake-blend-part-i/

http://shawnclover.com/2012/08/17/1906-today-the-earthquake-blend-part-ii/

...the rest is irrelevant. More from someone much smarter than I: http://davetrott.campaignlive.co.uk/2012/06/26/we-are-committing-a-category-error/#more-1243