Fifteen Central Park West is New York’s most exclusive address, an aerie of hedge-funders and celebrities, where a penthouse costs $40 million — and a wine cellar costs $80,000 more.

In researching my book, “The House of Outrageous Fortune,” I learned that F. Scott Fitzgerald was right: The rich are different.

Here’s a peek inside the $1 billion building:

IT PAYS TO BE THE HELP

A small army waits on 15 Central Park West’s residents.

There are seven concierges, six doormen, eight white-gloved lobby attendants, three package-room attendants, eight porters, a maintenance man, four security guards, 12 part-time engineers and an administrative assistant. Six people man Fifteen’s lobbies by day, two each for the doors, concierge desks and lobbies. Three more work the package room, and four porters and one or two engineers are always on duty.

Working at a building like 15CPW can be lucrative. Some titans of Wall Street tip very well.

The staff was excited when Sandy Weill, former chairman of Citigroup, handed out about $90,000 in his first year. But they were disappointed after that.

In 2008, he was “very generous,” says a former staffer, “but the second year they cut their tips in half.”

An ex-staffer recalls another early move-in, a former Goldman Sachs partner. It was December 2007 and he arrived bearing gifts, Christmas tips for everyone on the staff, even though he’d just met them.

The typical resident gives $100 to $500 to every employee, says a staffer still employed in the building. Music impresario Jesse Itzler tipped $650 a head. Fashion executive Elie Tahari, who rented, gave $300 and a $200 shirt.

In 2011, the typical employee’s holiday take was about $22,500. The concierges and anyone who does special favors “get more,” up to $100,000.

One employee thinks the resident manager, Gregg Carlovich, who was poached from the Time Warner Center, is the highest paid in the city, estimating he is paid $600,000 before tips, making him a truly super-intendent.

SMALL FORTUNES

The apartments of 15CPW not only are some of the most expensive in the city, they’re usually decorated as works of art.

One extreme example was hedge-funder Barry Rosenstein, who Forbes estimates made $140 million last year with his JANA Partners.

Rosenstein spent some of his take on his apartment, a 6,139-square-foot spread on the 16th floor (with 1,098-square-foot terrace) he bought for $29.5 million.

He either refused to have them installed during construction or ripped out all of the moldings, baseboards, flooring and trim designed for the building by architect Robert A.M. Stern, as well as some walls and the legally required rudimentary staircase.

His design team opened up the public rooms, dispensing with curtains and doors, aside from the five sets of French doors to the 10-foot-wide, L-shaped terrace. Solar shades that are invisible when retracted are the only window treatments.

The walls are covered with limestone-colored Venetian plaster and Japanese tamo paneling, and custom-crafted zebrawood floors were added. A heated wood floor went into a yoga studio.

LED lighting that mimicked natural light was installed on the ceiling of the switchback staircase to the 17th floor. Rosenstein filled the beige, pale gray and white apartment with modern art including two Warhols, a John Chamberlain car-crash sculpture, a small, early Roy Lichtenstein painting and a large Gerhard Richter canvas over the ebony-and-rosewood table and leopard-print chairs in the dining room.

Above the table hangs a delicate alabaster-and-bronze chandelier. Elsewhere, interior decorator Orlando Diaz-Azcuy placed an Axel Salto vase, Chinese bronze vessels, a Hiroshi Sugimoto photograph, a grand piano and a mix of mid-century modern antiques and spare modern furniture.

The Rosensteins’ desire for comfortable, informal furniture and fabrics led their decorator to nickname them Mr. and Mrs. Chenille. Money can buy you more than just stuff: It all took only eight months to complete.

A-ROD’S WOMEN

Despite all they see and all the fortunes housed above them, the 15CPW staff are still dazzled by celebrity, taking note when supermodels such as Naomi Campbell and Gisele Bündchen visited, respectively, heiress Andrea Kerzner or Jesse Itzler, or when Cameron Diaz left Yankee boyfriend Alex Rodriguez’s apartment, sailed out the front door and hailed her own cab.

“But sometimes you had to get a cab and bring it down to the garage to wait for her,” says a staffer. “I got hassles from the drivers, but I’d just say, ‘You’ll be happy when you see who you’re waiting for.’ ”

But fame alone was not enough to win the praise of Fifteen’s staff or its residents. Diaz “was way too nice for A-Rod,” the staffer continues. “He was a douche. No one liked him.”

An owner from the Morgan Stanley tribe agrees, describing A-Rod as “not a nice guy, an unfriendly narcissist.” That is likely why staff members tell tales they probably shouldn’t about the slugger, who was still married when he got to the building.

One day, his wife showed up — and said she was Mrs. Smith. “We didn’t know who she was, so we wouldn’t let her in,” says a former staffer. “Why didn’t she say who she was? She was uptight, nonresponsive and belligerent. When Alex came in 10 minutes later, we knew. He was with Goldie Hawn’s daughter.”

Fifteen became A-Rod’s home plate as he segued from dating Madonna (who lived a few blocks north at Harperley Hall) to Kate Hudson (whose mother, Hawn, lived a few blocks to the south at Central Park Place), and then to Diaz. But apparently, they weren’t enough for A-Rod.

“He got hookers all the time,” says the building staff member. “Usually two at a time, two times a week. One time he had two go up, they came down and left, and 10 minutes later, Cameron Diaz walks in. He doesn’t care. I hate the guy. He thought he was God.”

(A-Rod has denied all this.)

THE STOLEN PAINTING

One of the strangest stories from 15CPW involved the robbery of Bob Diamond’s apartment.

That crime occurred while Diamond was still the chief executive of the bank Barclays, which had just taken over Lehman Brothers’ investment bank and capital-markets units for the distress price of $250 million.

Diamond hadn’t moved in yet, but some of his possessions were there. Presumably, his security detail was watching him and not his stuff.

Residents of Fifteen carry electronic fobs that allow them to take the elevators from floor to floor. But those movements can be tracked by the security staff and its cameras. The only way to avoid being seen was to take one of the staircases that run behind the elevator cores.

It’s not known why the son of a neighbor in the tower decided to climb those stairs one day, only that he was on a break from a good school and his parents were away.

“He takes the back stairs up a few flights to Diamond’s apartment, it’s open, there are no locks,” says one of several people who tell the story. “He takes a painting and leaves it in his parents’ apartment. Diamond discovers the painting is missing.”

Diamond’s security team was called, but it was the building’s security staff that figured out what had happened and who’d done it from electronic records of fire doors opening; there were then no cameras on the back stairs. The thief “was confronted and he ’fessed up,” says a onetime building employee.

“Diamond was a real sport about it,” adds someone at real-estate company Brown Harris Stevens. It should probably come as no surprise that no charges were filed and the story of the incident has heretofore not left the building.

“That kid got very lucky,” says a renter who heard what happened.

Copyright © 2014 by Idee Fixe Ltd. From the forthcoming book “House of Outrageous Fortune: Fifteen Central Park West, the World’s Most Powerful Address” by Michael Gross, to be published by Atria Books, a Division of Simon & Schuster, Inc. Printed by permission.