Congratulations! You've been given $400M and The Railway Exchange. What are you going to do with it?

If a mischievous genie gave you $400 million and The Railway Exchange, with the stipulation that you had to spend all the money to develop the site into a viable business, what would you do?

I'm not very imaginative, so I'd probably play it safe with some kind of mixed commercial and residential development: shops and restaurants on the first couple floors, and the rest rentals or condos. But I'm sure y'all can think of something better.

Whatcha got?

Edit: I picked $400M because some expert was quoted as saying the redevelopment would cost about that much.