I think most San Franciscans now think of the bulldozing of the Fillmore neighborhood, which was a sort of "Harlem of the West" as the worst or urban renewal in the city.
This is the area cleared:
http://hoodline.com/2016/01/how-urba...der-to-save-it
This is what the Fillmore St commercial strip looked like "before" (in the background 2 large buildings are seen--on the left is the famous Fillmore Ballroom and on the right the "Peoples' Temple" of Jonestown infamy):
http://hoodline.com/2016/01/how-urba...der-to-save-it
Here's the demolition in progress showing some of the sorts of potentially beautiful Victorian homes that were turned to splinters:
http://hoodline.com/2016/01/how-urba...der-to-save-it