Monday night's episode of "" featured a guest who needed no introduction: former host .
Letterman hosted the show for over 20 years, from 1993 to 2015. His appearance was his first time he had returned to the Ed Sullivan Theater, where the show is filmed, since his retirement eight years ago.
The audience greeted Letterman with a warm welcome and applause as he sat down as a guest with Colbert. Even after he took a seat, the crowd continued to chant his name.
"Stephen, control your people!" Letterman joked. "This is the most enthusiastic audience I have been near since the night I announced I was quitting."
The comedian said it was a "delight to be back" and that plenty has changed around the theater since he left.
"It's like a mall! It's unbelievable. It's like Rodeo Drive," he said, referencing the popular Beverly Hills, California, shopping street and adding that his dressing room was nicer than any hotel he'd ever stayed in. "Ladies and gentlemen, this is the television of the future....I think it's delightful."
Letterman, who hosted over 4,000 episodes of "The Late Show," said he misses "everything" about hosting.
"Very few things in life provide one the opportunity...If you muck one up, you get to try again, and that's a pretty good device," Letterman said. "That was great. That made it more and more fun. And then when you do something that you're really proud of, you think, 'My God, let's do that again.' And six or seven years later, you have that experience once more."
Letterman has appeared on multiple late-night shows since his retirement, but as he told "CBS Sunday Morning" in 2015, he wasn't sure if his path would ever lead back to "The Late Show" and its home.
"I don't think I'll ever be back in this building again, honestly," Letterman said at the time. "I think it would be too difficult for me."
On Monday night, though, he returned to the most familiar part of the theater. Colbert invited Letterman behind the host's desk so the two could recreate a selfie they took in 2014.
"In my day, I never would've let this happen," Letterman joked. "We do this because my son doesn't believe I had a show."
for more features.