Since its opening in 1981, the Costa Mesa Historical Society operates a small museum, archive and local history library at this location. Operated by local staff and supported by volunteers, the museum is open to the public on Thursdays and Fridays or by appointment. Exhibits trace the history of the region from the earliest human inhabitants to the colonial period and the present. Special exhibits also highlight the unique history of the region during World War II, including Santa Ana Army Base (1942-1946). The base once occupied nearly twenty percent of present-day Costa Mesa.