Portrait In Black - Somebody Out There Knows
Sheila receives an alarming anonymous note - somebody out there knows! But who? Rivera in particular is shaken to the core.
Then ... They surreptitiously meet in a park to discuss their predicament The camera follows Sheila as she walks towards her lover, tracing out a panorama of the location.
... and Now, this is the Japanese Tea Garden in Golden Gate Park (map). The path they are on borders the east side of the Main Pond (arrowed on the detailed map below). The bridge in the center background is the Long Bridge, leading to the Pagoda in the center of the garden.
The Japanese Tea Garden was originally built on its present site in 1894. During World War II, when the word 'Japanese' became an anathema, it was renamed the Oriental Tea Garden, officially reverting back in 1954. A detailed map of today's 5 acre garden is shown below with the arrow marking precisely where this scene was filmed.
Then ... They walk a few steps along the path and perhaps overdo the guilty look as a warden cautions that the park will soon close. We now see a stone lantern behind them and across the pond steep steps lead up to the Pagoda.
... and Now, the same lantern may be listing, but it's still there, as too are the steps and the five-tieredPagoda. (Incidentally, the Tea Garden was also seen again eight years later in the movie Petulia).