Last time someone asked me this question, I was working in the buy-to-let department of the company I work for (boring mortgage company day job). My answer was "invest in buy-to-lets" and everyone thought I was joking. Except I wasn't.
So yeah, I'd invest in property. With that sort of money I'd buy myself a really nice place to live and buy a block of flats and let them all out. Somewhere where I'd get a decent amount of rent and live off the rental income. I'll look into other ways to invest money as well (on account of the ridiculously stupid amount of money that's mentioned in the OP), to get a decent return on the investments, i.e. more income. (I'll make sure I have the best financial advisor for all this.) I'm not that much inclined to a luxurious lifestyle so surplus income would probably end up going to various charities but of course I wouldn't go without anything that I wanted and I'd make sure my kids get whatever education they want without student debt or having to live off beans on toast for their whole time at uni (but I wouldn't give them too much because I don't want them to be entitled brats either... let them stand on their own two feet a bit. I'd help them get on the property ladder though and they'd inherit all my riches anyway.)
At some point (once it's all established and I have enough money to not need any other source of income), I'll turn to social housing, i.e. building affordable homes for low income people and families, with the rent money from those homes being invested back into the communities that live in them. You know, like how council houses were supposed to be run. And maybe fund a homeless shelter and/or other project(s) to help the homeless back into work and housing.
I'd probably end up supporting Monkey World Ape Rescue Centre (which is about a 30 min drive from me, yay!) in their work rescuing and rehabilitating apes and monkeys and also support work/projects protecting wild apes who are endangered, e.g. orangutans whose habitat is in danger from logging. I'll support various human charities as well though... humans are my favourite genus of ape.
I'll stay living here in sunny Dorset (probably closer to Monkey World though) but I'll have a second home in London, in zone one or two. Nothing too luxurious (cause London house prices are bloody ridiculous, even if you're a multi-millionaire).