And now there’s a movement to rebuild it.
Well... Not quite. Although there are many who would like the present eyesore physically removed. ;-)
What is being promoted is the conversion of the Farley Post Office building (designed by the same architects as and sited across 8th Avenue from the original Penn Station - now containing the thing that now carries that name stuffed under Madison Square Garden) or most of it into the "New Penn Station" which has been named the Moynihan Station after the senator.
Apparently the initial phase of the plan is to relocate Amtrak platforms, access and ticketing/waiting rooms to this 'new' section. Future plans indicate a new trainshed and who knows what else. That complete repository of the entire knowledge of the universe that calls itself Wikipedia has the following article that is about as accurate as stuff on Wikipedia gets..
Pennsylvania Station (New York City)
Whatever and however they do it, it is guaranteed to cost way more than it cost The Standard Railroad of the World to build the original..