Window to the Sky

It seems a stop work order has been posted at this Pacific Street/Boerum Hill address (# to follow) -- can't think why. The DoB permit posted says something about removing non-structural walls and various plumbing. But if you look closely at these photos, you can see through the windows to... the sky. And the other photo indicates that the backside of this former brownstone is... missing. Anyone know the story here?