Library of Congress
An original Keystone stereo card of an Irish street scene. Note now the lines of the road and row houses receding toward the horizon on the left and right sides add to the stereo effect. UC Riverside holds the Keystone archive, but The Library of Congress also has thousands of stereo cards like these available for download.
KPCC's Steven Cuevas visits UC Riverside's California Museum of Photography, which is the home to tens of thousands of stereoscopic images from around the globe.
Those pictures were snapped by photographers working for the Keystone View Company of Pennsylvania. They document life from the first half of the 20th century... and decades later, they deliver unmatched depth and clarity.