This was a bit of history I never knew:
"Wall Street bomb." Aftermath of the explosion that killed dozens of people in New York's financial district on September 16, 1920, when a horse wagon loaded with dynamite and iron sash weights blew up in front of the J.P. Morgan bank at 23 Wall Street. The attack, which was attributed to Italian anarchists, was never solved. 5x7 glass negative, George Grantham Bain Collection.
This is from Shorpy.com, a blog that has daily posts with really nice photography from the 19th and early 20th centuries. The photo above is actually just a thumbnail - go to the original post and click on the full size image. All of their photos are posted in huge, high-resolution scans.