What do these have in common?

Washington Apple Pi was faced with the choice of moving its office or paying higher rent. Eventually, the Pi negotiated with the landlord for a smaller space and lower rent. I took these photos along the Outer Banks of North Carolina, except the lower left photo which was taken at the Mariner’s Museum in Newport News, Virginia. The strange structure is a tank used as part of the restoration process for parts recovered from the USS Monitor, of Civil War fame. What do these have in common? (full size).

What do these unusual structures have in common?
What do these unusual structures have in common?

About lcharters@gmail.com

I started life as a child.