Home to the Doheny family for nearly 60 years, the Doheny Mansion was built in 1899 for the Oliver P. Posey family by architects Theodore Eisen and Sumner Hunt. Its eclectic Romantic Revival exterior unites elements of Gothic, Chateauesque, Moorish and even California Mission styles. The opulent interior reflects the wealth and status of pioneering oil baron Edward L. Doheny, who purchased the mansion in 1901 and, with his wife Estelle, led a fascinating life within its walls.

Left to the stewardship of Mount Saint Mary's University, the Doheny Mansion and all of the surrounding properties on historic Chester Place now form the University's downtown campus.