Dunsmuir House was built by Alexander Dunsmuir, who came to the Bay Area in 1878. The son of Robert Dunsmuir, a wealthy coal baron from Victoria, British Columbia, Alexander oversaw the family business in San Francisco.
When Alexander purchased the large estate in the rolling East Bay foothills, the land featured fruit orchards, farms and vestiges of the Spanish rancho days. The elegant mansion was built as a wedding gift for his beloved Josephine in December 1899. Tragically, Alexander became ill and died while in New York on their honeymoon. Josephine returned alone to her new home where she resided until her death in 1901.
In 1906, the estate was purchased by I.W. Hellman Jr. who worked for Wells Fargo Bank in San Francisco, as a summer home for his family. They dubbed their estate Oakvale Park. By 1913 the mansion was remodeled to accommodate the growing Hellman family and their acquisition from European travels.
The Hellmans enjoyed the estate together for fourteen years until Mr. Hellman died in 1920. Mrs. Hellman kept the estate, where her children and grandchildren came for long summer days, until the late 1950′s. During the Hellman era the landscaping at the northern end of the estate was developed, and the swimming pool and Dinkelspiel House were added to the estate.
The estate was purchased by the City of Oakland in the early 1960s with the intent of using the grounds and mansion as a conference center. A non-profit organization was formed in 1971 to preserve and restore the estate for the public benefit. For many years, the non-profit group and the City jointly operated the estate until 2010 when the City of Oakland became the sole proprietor.
The Dunsmuir Hellman mansion has been designated a National Historic Site by the United States Department of the Interior and both the Mansion and the Carriage House have been designated Historic Landmarks by the City of Oakland.