This image shows the reverse side of the Castro house, which faces the gardens. The balcony on this side appears to be a later addition, as it is not in the same construction style as the front, with support provided by vertical posts reaching to the porch below. There also appears to be an addition at the left, as the construction is also quite different from the main building.
The description states:
COURT YARD AT CASTRO HOUSE
San Juan Bautista
Erected in 1840-41 by General Jose Castro to house Secretary of Monterey District of Upper California House. Sold in 1848 to Patrick Breen of Donner Party.
–As indicated in the link, the Donner Party has it’s own unique place in California and Emigrant history. This card likely dates from the 1960s.