Then ... Still following leads to the murder of Jakes partner Evans, Larsen interviews Monica (Joanna Cassidy), the roommate of one of the victims of the bus massacre, a nurse.
Monica is a nurse, too. Larsen flashes his badge to her at the San Francisco General Hospital ward where she works and asks if there's a place they can talk.
... and Now, this has since 1981 been the famous Ward 86, the world's first in-patient HIV/AIDS ward; a reception desk now occupies the space where they stood. The window view looks to the west where Sutro Tower (nearing completion when the movie was filmed but not visible in the haze above) soars over the Twin Peaks skyline below.
Ward 86 is on the 6th floor of San Francisco General's Building 80 on Potrero Avenue at 22nd Street (map). The arrow points to that particular window.
Then ... She takes him across the corridor to a room that faces Potrero Hill to the east. He wants to know if she or her roommate knew Evans. They didn't but Monica's overt sex appeal catches him by surprise. When she tells him her roommate " didn't go out with ... men " he can't help but wonder about her too ...
... and Now, this room has since become an office - the window view is much the same, but that elevated water tower on top of Potrero Hill is no longer there.
Then ... She tells him to mind his own business but her departing over-the-shoulder come-hither look speaks volumes.
... and Now, the same corridor today. The reception desk, shuttered for lunch, is on the left.