The theatre is 16 short blocks uptown from Penn Station. A subway ride on the 1 train to 50th St. would be around 6-10 minutes. Walking would be around 20 minutes, though you'd be walking through the busiest part of town (Times Square), so you may want to give yourself a little extra time. A cab up 8th Ave should take a few minutes if traffic is light.
Should be less than 10mins by subway or 20min walk.
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