We don't have a writeup for The Theater at Madison Square Garden yet — check back soon.
4 Pennsylvania Plaza, New York, NY 10001 · Official site ↗
The Theater at Madison Square Garden opened in 1968 as the Felt Forum beneath the main arena, and it hosted a young Mike Tyson's 14th professional fight in 1985.
The theater sits beneath the main Madison Square Garden arena and is reconfigured for each show, so its capacity and room shape can vary a lot between events.
Nothing on Ticketmaster for this venue right now — check back closer to a date.