And where they are is rehearsing for their two plays: Pinter's "No Man's Land," and Beckett's "Waiting for Godot," which they starred in together in 2009 in London.
Sir Ian had so loved doing it back then, he pushed Stewart to revive it on Broadway.
After McKellen did "Godot" with Stewart, he wept when it was over.
"I recall vividly," laughed Stewart. "In fact, it's on film. I had no idea it was going to come. But the curtain came down on our last performance, and he went into the wings and sat on some stone steps and sobbed, heartbroken that it was over."
"Yes, I was heartbroken,' said McKellen. "And then we were going to say goodbye to each other. You were going off to do other things and I just felt I would never be as happy again."
The final performance was captured in a documentary called "Theatreland."
"I don't think you'll see me crying," said McKellen. "I think you'll hear me crying, 'cause I go into another room where the camera didn't follow."
"You're saying that my recollection of you sitting on the steps with your head in your hands is not accurate?" asked Stewart.
"Well, that's the nature of your own memory, and mine. I don't know," replied McKellen.
"This could be a moment out of either one of our two plays!" Stewart laughed.
Both "Godot" and "No Man's Land" explore aging and friendship, which apply not just to the two plays, but the Two Sirs as well.
"We are the same actor, really," said McKellen. "We've had the same career, really. Doesn't it feel like that to you?"
"Yes, very often," replied Stewart.
"So we're peers," said McKellen. "We're equals. We're not rivals."
WEB EXCLUSIVE VIDEO: Patrick Stewart and Ian McKellen on "X Men" & wizards (Click on the video player below)
The actor discusses with Lesley Stahl how playing Captain Picard changed his life.
The actor tells Lesley Stahl that "Lord of the Rings" fans are like "surrogate grandchildren."
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