This proposal looks beautiful, but a minor point stuck out for me. Putting large maps on the ceiling sounds like a terrible UX that will confuse people more than orient them.

You'll end up with one axis that corresponds to actual directions in the real world, while its perpendicular axis is exactly the opposite. If the "north" and "south" ends of the map are actually to the north and south, for example, east and west will be on the wrong sides.

If you put all four compass directions in their real-world locations, then the entire map is mirrored when seen from below. Maybe this rat's-eye-view of New York would be appropriate, but it would also be deeply unfamiliar and look like an enormous mistake.

There's a really good convention for public maps that are standing up on a sign (left and right correspond to what's to your left and right in the real world, and up corresponds to what's ahead of you), and there's a completely obvious convention for maps on the floor. There's no sensible convention for ceiling maps.