The Invisible Photograph, a five-part documentary series, investigates the expansive realm of photographic production, distribution, and consumption by way of the hidden side of photography, whether guarded, stashed away, barely recognizable, or simply forgotten.

From as far back as the drawings made within the dark interiors of caves, visual images have, from time to time, become “invisible.” The Invisible Photograph unveils rare or never-before-seen aspects of the photographic image through a series of episodes that will be released throughout the year. These documentaries, screenings, and discussions will demonstrate the unexpected challenges in the seemingly simple act of making, retrieving, and looking at an image.

Watch Part I: Underground to learn about the millions of photographs stored hundreds of feet underground at the Corbis Image Archive at Iron Mountain in Butler, PA.