Ralston Hall Mansion was the country estate of William Chapman Ralston, a prominent and powerful San Francisco financier who founded the Bank of California. Purchasing the property from an Italian nobleman in 1864, Ralston began construction of an increasingly grand mansion, ultimately comprising over 80 rooms. He called his estate "Belmont," a name that was subsequently adopted by the adjacent village.

In style, the exterior of Ralston Hall is Italianate Villa. The interior incorporates many features of the 19th century "steamboat gothic" construction and design, reminiscent of Ralston's early days on the riverboats of Mississippi before he came to California.

After Ralston's death, the estate was passed to his former partner, U.S. Senator William Sharon. During that era of the Mansion's history, one of the most elaborate celebrations was the wedding of Sharon's daughter Flora to Sir Thomas Fermor-Hesketh of England.

In 1922, the Ralston estate became the campus of College of Notre Dame. Chartered by the state of California in 1868, it is the state's fifth oldest institution of higher education. Known today as Notre Dame de Namur University, it continues the proud tradition as a premier master's university providing professional and liberal arts programs, with an enrollment of nearly 1,600 students.