When Charlotte Moore moved into John McMartin’s Upper West Side co-op, it was ‘not pretty.’ Nearly five decades later, that’s been fixed.In 1971, Charlotte Moore auditioned for “A Little Night Music” on the stage of the Winter Garden Theater, where the musical “Follies” was playing. (Readers will soon see that this is not an irrelevant detail.)Ms. Moore, who tends toward the dramatic, a trait that has likely served her well as a founder and the artistic director of the Irish Repertory Theater, insists to this day that her tryout, in front of the director Harold Prince, was “a disaster, a complete disaster — I was in tears and ruins, absolute ruins, embarrassed and humiliated.”But maybe not such a disaster. A year later, Mr. Prince phoned her with an invitation to join the fledgling New Phoenix Repertory Company. “When I decided to throw everything away and come here without knowing anyone at all, it was a ridiculous idea,” said Ms. Moore, whose adaptation of Dion Boucicault’s “The Streets of New York,” originally staged by her at the Irish Rep in 2001, begins performances there again, under her direction, on Dec. 4.“I knew nothing. But I just did it,” continued Ms. Moore, who grew up in a small farming community in Illinois, the granddaughter of Irish immigrants, and studied theater at Washington University in St. Louis.“I wanted very much for Jack to be comfortable,” said Charlotte Moore, who shared a one-bedroom co-op on the Upper West Side with her partner, the actor John McMartin, for more than 40 years.Katherine Marks for The New York TimesShe rented an apartment on Riverside Drive and began to settle in. Not long after signing the lease, Ms. Moore met John McMartin, one of the stars of “Follies,” which had recently closed. Now he, too, was part of the New Phoenix troupe.“I was madly in love with him on Day 1, although I didn’t know anything about him and hadn’t seen him in anything. I didn’t see ‘Follies,’ to my horror,” said the now 80-ish Ms. Moore.That lapse was apparently forgiven. A bit more than a year later, she moved in with Mr. McMartin, a divorcé who owned a large one-bedroom co-op with a private entrance on West End Avenue.She is still there. Mr. McMartin, who died in 2016, bequeathed the apartment to his two children, Ms. Moore said, “but he said specifically in his will that I am to be here as long as I want, and I would never leave.”During her first days in residence, she took the measure of her new home and found it wanting. “Jack had been living the bachelor’s life there since his divorce, and it was not pretty,” she said. “When I say, ‘Not pretty,’ that’s a gross understatement.”There was, for starters, a bed in the living room, mounted on two-by-fours. “Oh, my God, I was stunned,” she said. “I was stunned.”Charlotte Moore, 80-ishOccupation: Actor, co-founder and artistic director of the Irish Repertory TheaterMaking room: “We never did any structural work on the apartment. All I did was kind of refurnish the place, and arranged the spaces the way they were supposed to be.”Forty-five years on, the apartment is structurally as Ms. Moore found it. But she has determinedly changed it from crash pad to adult home.When outfitting the living room, she took her cues from her mother. “She hated modernity and loved classic rooms,” Ms. Moore said. Thus, the pale-green-and-gray velvet sofa with leaf patterning, the accent chair in a floral print, the nicely faded Persian rug and the four high-backed dining chairs that she inherited from her grandmother. Ms. Moore cleverly turned the foyer into a cozy TV room — she disapproves of televisions in living rooms, never mind beds — with a pair of chocolate-brown leather club chairs.Dark wood bookcases in the living room and TV room hold Ms. Moore’s many books about Napoleon (“I don’t know why, but I’m a Napoleon freak”); her books on Ireland (“Obviously, I have lots of books about Ireland”); and a mass of tiny glass and plastic pigs.Ms. Moore converted the foyer of the apartment to a TV room.Katherine Marks for The New York Times“I collect pigs, and Jack McMartin bought me a pig every birthday,” she said. “Napoleon and pigs — I don’t know why they go together.”While Ms. Moore summarily chucked some offending pieces when she moved in — goodbye to the hulking cabinet in the middle of the kitchen — she didn’t completely clean house. A much-loved breakfast table that was surrounded by a pair of rattan chairs and a curved banquette is still there. So is a hutch that holds her substantial cache of delft pitchers, vases, platters, cups and plates. Hanging above is a framed trio of Beatrix Potter illustrations featuring a rabbit, a gift from Mr. McMartin.Perhaps unsurprisingly, some of Ms. Moore’s favorite pieces in the apartment — the two flowered cushions on the banquette, the large, square wood coffee table in the living room and the vintage baby grand — are from stage sets. The piano has a particularly winning provenance: It was part of the scenery in the 1983 touring production of “Private Lives” that starred Elizabeth Taylor and Richard Burton, and featured John Cullum and Ms. Moore.“I’m not swearing to this, but I might have said, ‘You know, Richard, the only thing I hate to leave in this show is the damn piano. I love it so much. I think it’s so beautiful,’” said Ms. Moore, who composed the songs for “The Streets of New York” on that very instrument. “Well, one day, there it was, at the door of my apartment.”“All I did was kind of refurnish the place,” Ms. Moore said.Katherine Marks for The New York TimesMr. McMartin is very much a presence. He smiles from photographs. His books, many inscribed, still line the shelves. The gloves that were part of his costume in a Broadway production of “Chemin de Fer” hang in a frame near the living room. On a recent morning, Ms. Moore reached behind a bookcase and pulled out the cane that Mr. McMartin wielded during the shattering “Live, Laugh, Love” production number at the end of “Follies.”“Jack Cassidy came in here one time,” Ms. Moore said, referring to the Tony-winning actor. “And he said, ‘John, it’s time you did something with this place, because it’s a special place.’ I felt that way about it, too.”“I wanted very much for him to be comfortable and live in a pretty place,” she continued. “No, that’s not it. I wanted to live in a pretty place. I grew up in a nice house — a lovely house, actually — and I wanted this apartment to be wonderful. For both of us.”For weekly email updates on residential real estate news, sign up here. Follow us on Twitter: @nytrealestate. More