From the plaque:
The first building erected
as a cathedral in California, Old St. Mary's served the
Archdiocese of San Francisco in that capacity from 1854 to 1891. Once the
city's most prominent building, much
of its stonework was quarried and cut in China and its brick brought
"around the Horn" in sailing ships.
Plaque placed by the California State Park Commission in cooperation with the Paulist Fathers and the Grand Parlor, Native Sons of the Golden West, May 7, 1966.