Finn Wittrock stood outside Francesco’s, a hole-in-the-wall pizza joint on the corner of Columbus Avenue and West 69th Street, and peered forlornly through the window. A sign addressed to “our most valuable customers” announced that improvements were on the way, but not fast enough for this particular rendezvous.

Mr. Wittrock, 34, looked sheepish. As a college student, Francesco’s had been his old reliable. “After hitting the dive bar in the middle of the night, we’d come here to sober up,” he said, before adding pointedly, “it was always open.”

He had planned to reacquaint himself with his metaphorical madeleine, the cheese and olive pie, but no dice — or slice, even. A passer-by intervened to recommend a rival spot around the corner. “The plain is tasty,” she said. “And they play Mexican music.”

But that would not make for “the real Finn Wittrock experience,” as Mr. Wittrock himself put it. The real experience was not the pizza place around the corner that plays Mexican music. It was Francesco’s, followed by a walk in Central Park and beers at Malachy’s, an Irish bar on West 72nd Street where Mr. Wittrock, who spent four years at the Juilliard conservatory, celebrated his 21st birthday.

So Acts 2 and 3 were set, but what to do for a curtain raiser? Mr. Wittrock deliberated.

“That place, Empire Szechuan, was like the Chinese place,” he said, and pointed across the road at a maroon awning. His expression did not exude confidence.

Pizza-less, Mr. Wittrock walked south to take a look at Juilliard. He spoke fondly of his “rat’s nest” apartment, where rent included cockroaches. “Three bedrooms in what was the size of a studio apartment,” he said, cheerfully. “But I was 21, first time in New York, and I was with my two best friends from school.”

At Columbus and West 66th Street, Mr. Wittrock pointed to the broad glass expanse of his alma mater. “There it is,” he said. “It was this huge monolith back then. It wasn’t all glass, it wasn’t this fancy.”

It’s not only Juilliard that has gotten fancy since. Mr. Wittrock has, too, with a compact résumé of diverse stage and screen roles, most notably as one of Ryan Murphy’s eclectic ensemble, playing Fun House psychos and scrummy vampires in the campy fright fest “American Horror Show.” Mr. Wittrock’s latest role is as Judy Garland’s fifth husband, Mickey Deans, in “Judy,” the biopic that has been mentioned as an Oscar contender.

Turning east toward Central Park, Mr. Wittrock gestured to another shiny building that towered above the intersection. “That was an old deli forever,” he said. “I used to get black-and-white cookies there.”

Unlike the pizza, the loss of the cookies was less calamitous. “They’re not very good, but I thought it was a New York thing,” he said. “I also ate a lot of hot dogs, which I’ve never done since.”

After graduating he became more deliberate about his diet. To prepare for Angelina Jolie’s 2014 movie, “Unbroken,” Mr. Wittrock lost 35 pounds by eating whitefish and vegetables in two-hour increments and then fasting for 12 hours. “They say it’s how cave men would eat,” he said. “They would gorge and then not eat for a while.”

Was there a special diet to play Mickey Deans? Mr. Wittrock, who moved from his home in Los Angeles to London for two months to make the film, shook his head. “Just fish and chips,” he said.

Entering Central Park, Mr. Wittrock took a path that skirted Strawberry Fields south before looping east across the top of Sheep Meadow. The air was gluey with humidity. Mr. Wittrock, who was dressed in bluejeans and a white henley, pulled a baseball cap from his back pocket and slipped it on.

As he walked, memories tumbled out. In 2012, after an audition to play Happy Loman in Mike Nichols’s Broadway revival of “Death of a Salesman,” he’d found his way to the park “to breathe like a normal person for a second.” He landed the role. “I always associate this place with that,” he said.

Nearing the Mall, Mr. Wittrock looked down the tree-lined esplanade to place himself. “There’s the Shakespeare statue down there,” he said, indicating a spot far south. “I used to sit a lot under this flagpole and write poetry.”

What happened to the poetry? “It’s saved in a folder on my desktop.” In his spare time, he now writes film scripts, including “The Submarine Kid,” a small 2015 movie that has gained a second life on Amazon.

At the Bethesda fountain, he contemplated the skinny skyscrapers that needle the sky. A boat slid by on the lake. “I spent one time getting really high on a boat,” Mr. Wittrock said, before changing the conversation. “I have to tell you that I just had a baby,” he said.

The baby is a 6-month-old boy called Jude (he met his wife, Sarah, at Juilliard; they have been married since 2014). “For a baby, every new thing is so mind-blowing that it’s exhausting,” Mr. Wittrock said. “And every day it changes. What was really funny yesterday, he’s over it today.”

What was funny yesterday? “I did an Irish accent he thought was hysterical, and the next time I tried it, he was, like, ‘I’m bored, Dad.’”

Entering the thicket of the Ramble, the sounds of the city grow distant, almost imperceptible. Mr. Wittrock watched a cardinal hop around in the undergrowth and looked for turtles in the lake, which was turgid and neon green. “I feel they keep it this color so you won’t be tempted to swim,” he said.

After emerging on West 72nd Street, Mr. Wittrock made his way past the gracious apartment blocks — the Dakota, the Oliver Cromwell, the Franconia — and through the doors of Malachy’s. A Beach Boys song was playing. Tennis streamed on the TV screens crowding the walls.

After beers were ordered, Mr. Wittrock recalled summers running around the woods in the Berkshires, using sticks for sword fights. “I guess there is some significance to why I come to Central Park all the time,” he said.

Glancing around, he assessed the state of his old stomping ground. “It actually feels cleaner,” he said. “I think they’ve definitely mopped the floors recently.” He looked satisfied. “This is my loop, now complete,” he said, and took a long sip of his beer.