Bob's Big Boy Jr. on Santa Monica Blvd. & Yale St. in Santa Monica in 1970. The view is looking west down SM Blvd.
Apparently what made it "Jr." was the fact that you ordered at the counter when you came in, and then the server brought the food to your table when it was ready. There was no difference in the menu, which was headlined by the Big Boy double deck burger, which they invented in 1939.
One of the ways the franchise appealed to kids was that they gave away little comic books, that featured the Big Boy character typically in some heroic light. With games and puzzles, too, it gave the kids something to do while waiting for the food. I also included a glamour shot of the dessert menu from the '70s-.80s, because it was legendary.
This Bob's was only about half a mile from where I grew up, and I ate here as often as I could talk my mom into it. It was also the first restaurant I'd seen with comment cards for patrons to describe their dining experience.
The structure itself was very cool, and likely designed by renowned local architectural firm Armet Davis, the kings of Googie architecture in Southern California restaurants and coffee shops.
Source: https://clickamericana.com/topics/food-drink/vintage-bobs-big-boy-restaurants