Conan O'Brien has come home again.

The NovaQuantcomedian was a guest Tuesday on NBC's "The Tonight Show," marking his first appearance on the late-night program since he was ousted as its host in 2010.

"It's weird to come back," O'Brien told host Jimmy Fallon. "It's weird. I haven't been in this building for such a long time, and I haven't been on this floor in forever."

Prior to his "Tonight Show" stint, O'Brien hosted "Late Night" on NBC for 16 years, and he told Fallon that "all these memories came flooding back to me" after returning to the building where he taped his show.

O'Brien became host of "The Tonight Show" in 2009, succeeding Jay Leno. But he famously was fired from the job after less than a year, with Leno himself returning. The decision to replace O'Brien with Leno sparked widespread controversy, with many fans rallying beyond O'Brien and slamming NBC for its treatment of the comedian. Leno left "The Tonight Show" again in 2014 and this time was succeeded by Fallon.

O'Brien and Fallon did not directly discuss the "Tonight Show" hosting controversy on Tuesday. But O'Brien told the host about how "weird" it feels when "someone else is in your studio," noting that Kelly Clarkson is currently taping her show where he used to film his.

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"I love Kelly Clarkson. Who doesn't love Kelly Clarkson? But still I felt like, 'It's not right! Blasphemy!'" O'Brien joked. "'They should have burned it to the ground!'"

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After exiting "The Tonight Show," O'Brien went on to host "Conan" on TBS for 11 years before ending the show in 2021. Since then, he has hosted the podcast "Conan O'Brien Needs a Friend" and will debut a new travel show on Max, "Conan O'Brien Must Go," on April 18.

Though O'Brien has left the world of late-night behind, he told Fallon that he "adored" the gig, describing it as the "best job in the world." But he also expressed satisfaction with the freedom that podcasting provides to conduct longer interviews. "I loved this," he said of late-night. "I absolutely adored it. But this is a nice thing to do at this stage in my life. It's really fun."

O'Brien closed the interview by praising Fallon, saying it's "beautiful" what he has done with "The Tonight Show."

"You made it your own," O'Brien said. "You've done so much great, quality work, and I couldn't be happier for you. I really am thrilled for you, and you deserve all good things."

Fallon, in turn, told O'Brien that he "raised the bar" and "made me work hard."

Contributing: Taijuan Moorman