Artifact of the Day - World's Fair Rug

I think the idea of the World's Fair is a cool idea.  I wish I had been around for the early ones.  They look so fun!  I am obsessed with the 1933 and 1939 World's Fairs.

Vintage Inspiration July 13

Chicago's Water Building. Very inspiring. One of the few buildings to survive the Great Fire.

Below is the illustrious picture that got me kicked out of the water building. What was it's secret?

Is it Al Capone's vault?

Is it a Secret Passageway?

Or does it hold Pirate Treasure?

What do you think?