for the plane enthusiasts
These two air ships both were destroyed and many service people were casualties. A dig on that would be Historically informative for plane air enthusiasts.
As well a dig on the evolution of the 'Air Mail' map of the Universal Postal Union would provide a lot of insight on the advance of various aspects of trade.
the two ships in the photos are the USS Akron and the USS Macon, Navy airships of the early 1930s. Both lost.