Probably the most recognizable structure at LAX, the Theme Building's wide arches and UFO-like appearance scream retro-futurism. It is currently unoccupied, but the most recent tenant, the Encounter Restaurant, certainly left its mark. Designed by Walt Disney Imagineering in 1997, their new interior added even more retro chic with bright colors and groovy patterns.
The building opened in 1961 and has been occupied by a number of businesses. Since the Encounter shut down at the end of 2013, it has remained empty and is a great spot for those urban explorers out there. It's fun to prowl the dead UFO in the middle of one of the busiest airports in the world -- definitely a good place to get your philosophical pondering on. The guard on duty was very friendly and had no problem with letting us explore on our own.
Oh, and don't forget to hit the observation deck on the top floor; it's a great panorama.