Wonder Wanda wins with her 5:53 p.m. Tuesday guess "The lattice-work structure makes me think this is actually Gwinn's Drive-In Restaurant on Colorado Blvd in Pasadena. It has been through many iterations since then."
In the photo above, a carhop serves customers in an automobile at Gwinn's, a restaurant and drive-in far from downtown Pasadena at 2915 E. Colorado Blvd. It was on the north side of the street between Sunnyslope and El Nido.
I purposely cropped out the Gwinn's sign. Here's the full-frame photo:
Colorado Boulevard was an important link on Route 66 and Gwinn's, open from 1949 to 1972, had the iconic mid-century roadside architecture to fit right in with classic styles all along the "Mother Road" from Chicago to Santa Monica.
The restaurant, with inside dining and outside car service, was designed by Harold J. Bissner and R. Harold Zook.
Here you can see indoor diners and servers:
Inside and out, Gwinn's was a popular gathering place for everything from business meetings to date night. The idea for the Pasadena Beautiful Foundation began over dinner there in 1960.
This paper placemat showing the 1958 Rose Bowl Game results (Ohio State vs. Oregon) recently sold on ebay for $24.
Sadly, the building was demolished a few years ago.