Monday's finale to Crosby, Stills & Nash's international 80-date tour may have been one of the more memorable gigs of the group's career. Concluding a string of five nights at New York City's Beacon Theatre, the trio hearkened to 1969, showcasing the first-ever complete performance of their self-titled debut album.

But that wouldn't come until the evening's second set, Graham Nash informed a crowd who seemed almost entirely to hover within a couple decades of his own 70 years. The walking spectrum of graying hair had murmured words like "memories" and "remember" many times as they filed into the gilded concert hall moments before Nash's introduction. Some parents brought teenagers in tow; others settled for telling their seat mates about rediscovering CSN's catalog alongside their children.

Final Song of the Tour: "Teach Your Children"

The three-pronged harmonies began immediately with the Crosby, Stills, Nash & Young tune "Carry On," with a barefoot Nash at center stage, a sturdy and merry Stephen Stills to his right, and David Crosby to his left, looking as if one of J.R.R. Tolkien's dwarves grew three feet and shaved the epically long beard but kept the mustache. A smattering of attendees seemed unprepared to take the show sitting down, with isolated seat-dancers standing sporadically throughout the night. (And how refreshing to see a group of people who not only obeyed the prohibition of photography but even seemed unfazed; a band witnessed without a sea of screens is the modern concertgoer's needle in the haystack.)

For a crowd in full knowledge of the historical treat forthcoming, one might have expected reserved enthusiasm for the early portion of the show. One would have been wrong - the full crowd rose after the second song, the first of a couple dozen standing ovations. For a band whose songs have been locked in amber by soundtracking so many American memories, the music sounded refreshingly immediate. Through newer songs and classics, hits and deep cuts, the three brothers in song were entirely invested in their performance. Skipping the notion of an opening act, CSN played something in the neighborhood of 30 songs, holding the stage for the majority of three hours with an intermission between sets.

Crosby tried out a recently written, as yet unreleased song titled "Radio," and the reception was not an exodus to the restrooms but applause on par with the beloved chestnuts. Nash, taking a brief break from his theatrical hopping and miming, took to the electric piano to perform "Our House" as a tribute to his newborn first grandchild, inciting the night's first gigantic sing-along. "Love the One You're With" came shortly after, also igniting the crowd's fullest excitement.

Though deft and busy, the five-piece backing band felt invisible behind the famous threesome. One song, "Lay Me Down," was touted as having been written by Crosby's son James Raymond, who manned the evening's keyboards. Nash and Crosby simply stood and harmonized, instrument-less, Nash with a glass of wine in hand.

"My job is to write the weird shit," Crosby said in response to detractors wondering what exactly he does in the band. That segued into the title track from 1970's "Déjà Vu." Crosby would showcase his fanciful side again, playing "Guinevere" during the "Crosby, Stills & Nash" run-through.

The first set concluded band-less, with the three icons alone at center stage; "Suite: Judy Blue Eyes" began in the same terrific fashion, just three voices and one guitar as strummed by Stills. The uninterrupted spin through the self-titled album included highlights in the always-buoyant "Marrakesh Express," the absurdly energetic "Wooden Ships," and a fierce rendition of "Long Time Gone." The thrill of honoring the record that had introduced them to the world never seemed to waver. "And there you have it," said Crosby at the close of "49 Bye-Byes." "Never been done before," added a visibly proud Nash. There was a thunderous approval for even more, and a half-dozen additional songs followed.

The night ended with a loudly sung cover of Stills' timeless Buffalo Springfield tune "For What It's Worth," followed by a near-deafeningly sung "Teach Your Children." If anyone was disappointed, they hid it well.