House.
With such a silly amount of money, one's life can be whatever one wishes for.
As for FIRST (#1) purchase, I chose a house, a base for my further developement of my life. I would build it in a spot where I have access to my own water source and where I can be self-sufficient in energy, preferably solar panels, but wind energy is fine too. A completely recyclable house, where all waste (as far as possible) will be re-used and with a greenhouse that can provide basic vegetables.
After that I would probably use my fortune to fight for those less fortunate, for women's rights, for democracy, the limitation of governmental power and for freedom of the individual in general.
Ahh, all that wishful thinking...