Chelsea Clinton bought New York’s longest apartment – stretching an entire block from 26th Street to 27th Street off Madison Avenue – for $10 million.

The apartment is described as “a luxury fortress” with one full-time doorman to the horizontal building’s four units, it takes almost 30 seconds to walk the 250-foot hallway, according to New York Daily News.

Chelsea Clinton, 33, bought the four-bedroom, 5,000-square-foot apartment with her husband Marc Mezvinsky, 35, after putting their nearby $4 million pad on the market earlier this year.

The building, which is being marketed by Douglas Elliman Real Estate, has one apartment on each floor and boasts various security features, including a key operated lift and one doorman for just four units.

The nearly 90-year-old building has just three $10 million homes and one $22.5 million duplex penthouse – so far two buyers are in contract, including Chelsea Clinton.

Apparently other big names are looking at the remaining units, which are billed as among the most secure in Manhattan.

Chelsea Clinton bought New York’s longest apartment, stretching an entire block from 26th Street to 27th Street off Madison Avenue

Melanie Lazenby and Dina Lewis, who share the residential building’s listing, said the hallway is “the wow factor” but exclaimed: “There’s a full-time doorman for only four apartments. I don’t know any other building with that kind of personal service.”

Chelsea Clinton and Marc Mezvinsky’s apartment has six and a half bathrooms, a home office and den, plus a 252-square-foot planting terrace and a private storage unit.

The couple will also enjoy two dishwashers, two washer/dryers, his and her maze-like closet spaces and commodes, as well as natural light flooding the female dressing room – with double-sided vanity mirrors.

“Wives eyes light up when they see the closets,” said Melanie Lazenby, the daughter of James Bond actor George Lazenby.

“They smile and say they’ll need more clothes to live here. Their husbands just shake their heads.

“The long apartment, located at 21 East 26th St enables one spouse to be fast asleep while the other has a huge dinner party. All on one floor,” she added.

One person who toured the building, which was built in 1924 by luxury textile manufacturer Clarence B. Whitman & Sons, joked that residents of The Whitman will have a longer walk to their kitchen than many New Yorkers have to the corner store.

Chelsea Clinton and Marc Mezvinsky’s current apartment on Fifth Avenue is far from shabby – boasting three bedrooms, two bathrooms as well as a gym and doorman.

Located in the Grand Madison – a building that has been dubbed “the most elegant and historical building downtown”, the 1,922-square-foot boasts “unforgettable views” over downtown Manhattan.

According to a Douglas Ellisman listing, Chelsea Clinton and Marc Mezvinsky’s $4 million “starter pad” has a powder room, an open chef’s kitchen with beautiful bluestone countertops, oak floors, Italian marble bathrooms, huge windows and scores of other luxury finishes.

Assuming a 4% interest rate and 20% down payment, Chelsea Clinton and Marc Mezvinsky’s already-hefty mortgage payments total around $18,460 a month.

According to StreetEasy.com, if they put down a $2.1 million – or 20% – deposit on the new $10 million home, their monthly mortgage bill will be in the region of $52,000 and closer to $60,000 if the couple handed over a 10% down payment instead.

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