I'm sure this has been discussed here ad nauseam, but I don't understand why they aren't returning the sphere to the WTC plaza. They claim there is no where for it to go, but I found a spot. Put it just to the north of the Museum entrance, on the corner of Greenwich and Fulton Street. It would be a central point in the WTC, it would welcome people to the Memorial Plaza coming from the transportation hub, and most symbolically, it will only be a few feet from where it was originally installed.

It should be installed where I have placed the red dot.