Charles Blondin had been walking the tightrope since childhood, and had entertained Americans for a decade by the time he crossed Niagara Falls. So his fame preceded him, and a photographer from the London Stereoscopic Company arranged to be on the scene to capture images of the astounding stunt.
In this photograph by William England, Blondin is shown hundreds of feet in the air above the Niagara River. To be precise, Blondin didn't walk above the falls, but actually crossed the Niagara River about a mile north of the falls.
Blondin's first crossing of the Niagara River by tightrope was on June 30, 1859, but it's probable that this photograph was taken during a later crossing that summer.