Any Ideas As To Where This Has Been?

By the looks of it - Everywhere

Gee, The marker monkey was alive in 1939!

1909 I think is the year.
This is my best guess . . .

It went from Bangor, Maine to Cairo
From Cairo to Giura?
From Giura? to Giza
From Giza to Washington, DC (Dead Letter office)
From Washington, DC (Dead Letter office) to New York
From New York to Bangor, Maine

Are we there yet?

Nice detective work Smauggie !

My guess is that it made the three stops in Cairo as Smauggie suggests, and that Postage Dues [1889 issue] were added along the way.
The 4mil and 1mil on the left look like the first ones to cover lack of postage from the USA.
Next to those are the 1 piastre and 2 mil with Gizera cancel but I cannot read the cancels clearly so I may have it wrong.
It's 3rd stop was Giza, again with 1 Piastre and 2 mil Dues.
Louise certainly moved around a bit !

Nice Flag cancel [yes, I did notice !] and 'T' handstamps. I love the 'Return to Sender' handstamp too.

Great cover. I wonder if it was ever reclaimed or if it spent a long time in the Dead Letter Office.
And where did it go from there...........

Londonbus1........

more evidence to verify the statement....
"Maine...you can't get there from here?"

sender must been some kind of prophet, and he knew about the long route of this envelope, so he use the large one to has enough space for all stamps and postmarks