In 1922, Scott and Zelda Fitzgerald, new parents and pinched for cash, gave up their suite at the Plaza Hotel and rented a house on Long Island in Great Neck. The rent was $300 a month, compared with the $200 a week they were paying at the Plaza.

Located at 6 Gateway Drive, the house was pleasant but modest. Zelda called it their “nifty little Babbit home.”

But nearby were more than 1,000 country houses of the Gilded Age, vast estates belonging to the Goulds, the Guggenheims, the Astors and the Vanderbilts.

Flashier money was there, as well. Hollywood was in its infancy, so New York City was still the center of the entertainment world. Eddie Cantor, Ed Wynn, Groucho Marx and Samuel Goldwyn all had houses on the Gold Coast.

There were also a few mobsters throwing around their ill-gotten gains from bootlegging.

Never a couple to miss a party, Scott and Zelda mingled with everyone, drinking Champagne, splashing about in pools, playing lawn tennis and having flings.

It was in this atmosphere of money — old and new, elegant and garish — that the idea for Fitzgerald’s most celebrated novel, “The Great Gatsby,” took shape.

The Fitzgerald house is up for sale for $2.999 million. It’s been expanded over the years, but it still looks like it did in 1922.

The Gold Coast itself does not. What was once a pastoral escape for the superrich has become a sprawling suburb, with condominiums occupying tracts of land that were once polo fields.

But the geography is the same, and here and there you can catch glimpses of places that may have inspired “The Great Gatsby.”

Fitzgerald famously named the two peninsulas that jet out into the Long Island Sound “East Egg” and “West Egg.”

He liked the word egg, calling friends “colossal eggs” and enemies “unspeakable eggs,” writes biographer Jeffrey Meyers.

East Egg — where the old money lives in the novel — is Sands Point on the Port Washington peninsula. West Egg — where Jay Gatsby, emblematic of new money, has his mansion — is Kings Point on the Great Neck peninsula.

“The North Shore colony developed because of its easy access to New York City,” says historian Paul Mateyunas, author of “Long Island’s Gold Coast.” The Fitzgeralds’ Great Neck house is within walking distance of the Long Island Rail Road station.

Never a couple to miss a party, Scott and Zelda mingled with everyone, drinking champagne, playing lawn tennis and having flings.

“It was untouched by industry, so if you were rich, you had rolling hills for fox hunting and deep harbors for your boat.”

The best way to see the mansions on both peninsulas is from the Manhasset Bay. I took the Great Gatsby Boat Tour, which is led by amateur “Gatsby” historian Eleanor Cox.

A few old-money mansions are still standing on the Port Washington side. Jock Whitney’s massive hunting lodge is intact. The enormous window on the top floor looks into what was once his trophy room.

An elegant white house with dormer windows is thought to have inspired Tom and Daisy Buchanan’s mansion. The ceiling in the main room, says Cox, resembles the “frosted wedding cake of a ceiling” Fitzgerald describes in the novel.

The flashy mansions are on the Great Neck side. And most of them are ghastly. One belonging to a doctor looks, as Cox puts it, as if it’s made out of tongue depressors. Another, a sprawling amalgam of clashing French styles, could belong to a James Bond villain.

It has underground parking for 30 cars, yellow Lamborghinis, no doubt.

If you’re looking for the house that inspired Jay Gatsby’s party mansion, you’re out of luck. As Mateyunas points out, the house was a composite of several estates Fitzgerald would have visited, on both sides of the bay and in other towns along the Gold Coast.

Beacon Towers on Sands Point, which was owned by Alva Vanderbilt Belmont, is thought to be one of his inspirations. All that’s left of it are the garage and the gates.

Another possible inspiration, Oheka Castle — with 127 rooms, the second-largest private home in America when it was built in 1919 — is still standing, though it’s a few miles east, in Huntington.

Built for Otto Kahn, it was the site of many celebrated Gilded Age parties. Although there is no record of Fitzgerald ever having attended any of them, he would have been familiar with the house through newspaper reports, says Mateyunas.

Very Gatsby-ish, it’s now a fancy hotel.

One of the best-preserved Gilded Age mansions is Falaise in Sands Point. Modeled on a French country manor, it was built by Harry F. Guggenheim in 1923. Charles Lindbergh, one of Guggenheim’s close friends, was a frequent guest. His station wagon is still in the garage.

Guggenheim died in 1971, leaving the house and most of its contents to Nassau County. It’s now a museum, and well worth a visit, though it’s doubtful Fitzgerald ever set foot in it.

The Fitzgeralds only lived in Great Neck for two years. Once again, their spending habits — and partying — caught up with them. Fitzgerald put all his “eggs,” East and West, in one basket, hoping that his Broadway-bound play “The Vegetable” would be a hit.

When it flopped, he “was forced to go on the wagon and write himself out of debt,” writes biographer Meyers. He retreated to an unheated room above the garage at 6 Gateway Drive and churned out indifferent articles for popular magazines of the day.

In 1924, he and Zelda sailed to the French Riviera, which, improbable as it seems today, was cheaper than Great Neck.

And it was there that he fashioned his impressions of the Gold Coast and its privileged partygoers into “The Great Gatsby.”