One Hundred Million!

Imagine that I found 100 million euro somewhere. In cash.
I found them, no one else is going to claim them, they are mine.

How would I go about inserting that money into the economy of the world?
How do I get them from their fairly unwieldy current form into something more usable, say, a bank account? I can't very well run around and use cash all the time. The economy just doesn't work that way. Besides, what if I get robbed?

How would I go about it? How would you go about it?
What are the advantages of the various ways? How do you do this without having to either pay undue fees, or get the government breathing down your neck about the whole thing (the suspicious, tax collecting lot that they are)? Would I have to launder it, even though it is mine?

Please provide your answers below.

For that matter, if you know, what is the physical size of 100 million euro. A wad? An attaché case? A crate? A truck?