Lisa Oppenheim uses appropriated photographs from diverse sources such as government files and online photographic archives to investigate collective memory, loss, and forgetting. She is keenly interested in the magic of photography, collections of visual history, and images that eerily represent both absence and presence. In Art for the Public: Images from the Collection of the Port Authority (2009), Oppenheim re-photographed a 1986 art catalog that depicted the public art collection managed by the Port Authority of New York and New Jersey. Some pieces in the collection were stored in the World Trade Center, and the objects Oppenheim re-photographed had been destroyed during the terrorist attack on 9/11. In a 2010 series of "Lunagrams", she used original 1851 negatives to create a series of lunar portraits. The negatives are the earliest known photographic images of the moon.