Complex sentence: Built in the late 1920s by Standard Oil Company, the building housed a U.S Experimental Station in the early 20's that began flying mail for the US Post Office, and soon started a flying service which evolved into Delta Air Lines.
Split into simpler sentences: Built in the late 1920s by Standard Oil Company, the building housed a U.S Experimental Station in the early 1920s that began flying mail for the US Post Office. It soon started a flying service which evolved into Delta Air Lines.