As promised, here's the expanded view of yesterday's photo showing the glass blocks. It's the local McDonald's done in a retro 50's style and called a McDiner. Along with the glass blocks are lots of neon and "Speedee" above.
There is a local connection to the McDonald's company here also. In 1937, Patrick McDonald opened a restaurant called the Airdrome at the (now long gone) Monrovia Airport. The restaurant was later moved to San Bernardino and renamed McDonald's. Years later Ray Kroc bought out the business and turned it into the empire we know today. While San Bernardino is considered the home of the first McDonald's, the roots go back to Monrovia. - Source: Wikipedia.
Update with additional links:
Abandoned and Little Known Airfields: California - A little more history and photo's.
Pomona Public Library - A photo from the airport.
Monrovia Airport tile mural at the Monrovia Albertson's - 2 previous posts here and here.