Not far off California Route 66, we stopped at the Original McDonald's Museum in San Bernardino, California. This is the site of the original McDonald's, Dick and Mac McDonald founders.
In 1940 they moved the Airdome building to San Bernardino at 14th & E St., and it became McDonald's Barbecue Restaurant. In 1953, the brothers began franchising their fast-food system and closed their successful restaurant, reduced their menu to cheeseburgers, hamburgers, milkshakes, and fountain soda. They demolished the octagonal building and built a new restaurant with two golden arches designed by Dick McDonald.
In 1954, McDonald's #4 opened in Downey, CA, which remains open to this day. Back to the Original McDonald's Museum. A local (Albert Okura) fast-food franchise company (the Juan Pollo restaurant chain) now owns this site as well as the classic Route 66 town site of Amboy, CA. Mr. Okura is an avid Route 66 enthusiast and supporter, turned this site into a museum (unofficial museum).
Source: "Original McDonald's Museum," The Sun, Jan 22. 2019.
The Museum contains the most extensive collection of McDonalds memorabilia such as news article, pictures, and mementos such as menus, straws, cups, a prototype of ketchup dispensing gum, a copy of McDonald's menu, etc., that were donated by people.