The collection consists of research files on Seattle and Northwest photography and history, and Cirelli’s collection of photographs of Northwest subjects, largely by photographers who worked or lived in Seattle. The bulk of the materials dates from the late 1800s to the early 1900s.

The direction of Cirelli's research was informed by his focus on photography and the photographic record of early Seattle, Washington State and (to a lesser extent) Northwest history. The collection reflects the branching nature of his research; in addition to files on particular photographers, the collection includes files on the people, places, and events that were the subjects of early regional photography. So while Cirelli collected materials on established photographers like Frank LaRoche, the Lomen Bros. and Webster and Stevens, as well as on lesser known photographers, he also accumulated materials about Washington Territory pioneers, local politicians, prominent families, and picturesque local characters (such as Seattle’s “Umbrella Man,” Robert Patten), as well as on buildings, neighborhoods and events. In addition to the subject files, the collection contains a large amount of materials which remained unsorted at the time of Cirelli’s death, mostly photocopies, transcribed articles and notes.

The photography collection provides examples of work by many of the major photographers of the Northwest, largely photographers based in Seattle. Most of the photographs depict people and places in Seattle and Washington State, but a few depict other Northwest locations such as Alaska and British Columbia.

The collection also includes two sketchbooks created by Seattle pioneer Alfred M. Schillestad.