The Flit
“What’s the Flit? A bad altitude. The Flit is where you go when you're no longer welcome at ground level. Or if you really rate a good view from your window.”

London's hidden aerial district, located above Spite and constructed out of ladders and rope bridges between the rooftops and chimneys. Here you'll find shadowy sorts: criminals, spies, urchins, and even revolutionaries. It's the perfect place to plan heists from, granting accessibility to practically everywhere. Essential for casing and carrying out the heist itself.
You'll need to bribe the urchins for a way in, but once you've learnt the ropes, as it were, you'll be fine. (Just be careful during the races. It's humiliating at best, tumbling down into Spite.)
In-game, as your Shadowy rises above 60, you will unlock more content in the Flit.
Original by NiteBrite/Mrs. Brite