An Exploded View Drawing of Madison Square Garden, 1967
According to this Deadspin article, New York City has basically given the owners of Madison Square Garden ten years to find a new place to play. The arena, which is the fourth to bear that name, opened on February 11, 1968 on the site formerly occupied by the above-ground portion of Penn Station. Apparently New York wants to undo that architectural crime, and so here we are.
Not to get all nostalgic or anything, but I thought it worth taking a quick look back at MSG IV's early days. Here's a neat exploded view drawing of the Garden from the November 1967 issue of Popular Mechanics. It shows the main areas of the building by function.