The 1920s came roaring through Brooklyn and Queens on Saturday.

Decommissioned subway cars dating to the New York City subway system’s youth time-traveled along a ceremonial “nostalgia train” route, tucked between regular A and shuttle train service.

“Look at it. Listen to it,” Vietnam vet Stanley Reid, 71, of the Bronx, a retired motorman, conductor, dispatcher and boss, said aboard a BMT D-type built from 1925 to 1928, which ran for regular service until 1965. “Ride the A train and tell me if you feel the same thing.”

The seats, rattan cane (replaced with plastic in later builds). Ceiling fans whirred above. Bare incandescent light bulbs flickered (the threading, the reverse of home fixtures, to prevent theft). A separate conductor worked each car, to open and close doors and make announcements, pre-loudspeaker days.

“MEET MISS SUBWAYS of MAY, 1942,” one ad above said, the “lovely” system mascot.

“Never worry about odor again!” read an ad for Dial soap.

One ad touted 9 cent salad dressing, 10 cent mayonnaise and cereal, 2 boxes for 29 cents.

On Saturday, advance tickets were required, to be bought from the New York City Transit Museum, the trains’ usual home: $35 for museum members; $50 for everyone else.

“Some random Joe Shmoe can’t just get on the train,” said a museum volunteer.

At the terminus, Beach 116th Street, a clique of Joe Shmoes and a Jane Shmoe, all unauthorized transit enthusiasts, shouted out train car numbers, marveling at the old-timey motorman controls and recording the trains’ distinct purrs, whooshes, shrieks and clicks, comparing the sound to existing YouTube videos of the same.

Daniel Kotlyarskiy, 19, of Brooklyn, a city public school IT guy, stood on the platform, an A-train hat on his head (“I bought it special for this trip”), an N train pin on his T-shirt (“I always wear this pin when I’m rail-fanning. Always.”) and a camera dangling from his neck.

“They’re very ornate. They’re very pretty. Elegant. Way back when the trains were luxury,” said Kotlyarskiy, who challenged a reporter to name two points in the city’s 469-station system, so Kotlyarskiy could recite travel directions by heart. He was right every time.

Kotlyarskiy carries a folded-up printout, relevant sections highlighted, of the MTA’s rules permitting him to photograph the transit system — in case challenged.

Councilman Eric Ulrich (R-Queens) sat on one of the rattan-covered benches on board, waiting his turn to look out the train car’s panoramic front window, “a magical place for everyone!” Three of the enthusiastic volunteers were monopolizing the view, five or more cameras, recorders and iPhones between them.

Later, Ulrich pointed to the ceiling fans. One wasn’t on.

“This one doesn’t work, so we know it’s really run by the MTA,” he said. “Just kidding.”