As famed singer Judy Collins celebrates her 85th year, she’s hot stuff. But of course she has been since 1962 when she was on the forefront of the folk movement that launched her, Bob Dylan, and Joan Baez to dizzying heights.

Collins even has a feature last week in The New Yorker.

So why not celebrate 85 in fashion? Last night she filled New York’s Town Hall, the same place she played her second ever show back in ’62. She and the building have held up very well. On stage she welcomed her old boyfriend, Stephen Stills, plus Sophie B. Hawkins (who turned to be a most winning emcee), “Wicked” composer Stephen Schwartz, the astonishing Paula Cole, and Martha Redbone, Ari Heist, and many other collaborators including Fairport Convention legend, Richard Thompson.

Legendary Warner Bros. record producer Russ Titelman worked on the sound and it was probably the best show anyone’s heard in Town Hall or any theater in ages.

Collins is a full-throated smooth operator on stage, ever so comfortable telling jokes off the cuff, reading from a tight, punchy script recalling her amazing journey in music, and showing off her trained classical pianist moves. She’s also a pretty good guitar player.

But it’s The Voice. There’s a TV show called “The Voice” but nothing equals Collins’ clear as spring brook water tones even after 60 something years. The Voice sounds like what you imagine Colorado to be, and when she sings about her birthplace you feel like packing up and going there immediately.

Yes, she sang her hits like Stephen Sondheim’s “Send in the Clowns” and Joni Mitchell’s “Both Sides Now.” Her version of the latter was the original, of course, making Joni’s recording a cover of her own song. The difference now is that Joni performs it with great drama and intensity. Collins’ take is almost a pop arrangement counterpointed by disarming phrasing that makes the clouds seem less threatening and more like the kind you see in great paintings.

Collins also delivered some acapella moments, on songs like “Where Have All the Flowers Gone” and Leonard Cohen’s “Suzanne.” (She made Cohen famous.) Her reading of “Who Knows Where the Time Goes” with Thompson was incredibly poignant. With Schwartz on piano, she sang a duet of “Somewhere Over the Rainbow,” with Schwartz singing and playing piano on that song for the first time ever. Considering his attachment to “The Wizard of Oz,” it was a once in lifetime moment.

The guests did not let us down. Rickie Lee Jones’s version of “Mr. Tambourine Man” turned Dylan’s Byrds hit inside out. Cole — who had big hits in the 1990s and then fought for decades with her record company — emerged as a classic talent. Beth Nielsen Chapman was outstanding. Martha Redbone — performing at the Apollo soon — is a roots revelation, an overnight sensation after 40 years. (Her emotional performance last night reminded me of Rhiannon Giddens singing years ago at Town Hall.)

Well, they filmed the whole thing last night with about 20 discreet cameras for a long needed documentary about Collins’s life as a singer, songwriter, and activist, not to mention poet. Yes, she has a book of poetry coming out next month because…why not? The night, by the way, ended with everyone on stage singing the final section of Stills’ “Suite: Judy Blue Eyes,” the song he wrote for her in 1968 that has lasted our lifetime.

One last thing: Taylor Swift and her proteges like Gracie Abrams don’t realize how influenced they are by Judy Collins. Swifties would do well go to back and listed to albums like “Bread and Roses.” They’d be mesmerized.