From the plaque:
This example of early California
architecture was built in 1850-53 by Raimundo Yorba. Purchased
in 1868 by Fenton Mercer Slaughter, it was preserved as
a memorial to him by his daughter, Julia Slaughter Fuqua.
Plaque placed by the California State Park Commission in cooperation with Ontario Parlor No. 251, Native Daughters of the Golden West, October 2, 1960.