As I was refiling some photographs, I came across this stereograph taken of Memorial Chapel in 1893. I’m afraid I don’t know what the event is. These cards are also called a steropticans, stereograms, or stereo views. When you look at them through a stereograph viewer (shown below), the two images merge into one 3-D image that is quite startling in its reality. You can read more about stereographs here.
Stereograph viewer photo credit: http://www.nps.gov/anti/historyculture/photography2.htm