Tour the Gilded Age Manhattan townhouse where Jackie Kennedy's favorite designer worked

The sale of the House of Cassini caps a 125-year history of transformation.

Built steps from Fifth Avenue's "Millionaires' Row" as a stockbroker's statement home in 1901, the stately limestone dwelling was subdivided into apartments throughout the '60s and '70s.

And in the decades until his death in 2006, Cassini designed glamorous mass-market wedding gowns and sketched fashions for longtime client "Jackie O" by the light of a towering window spanning the six-story home's two topmost floors.

Before diving into the home's tumultuous history and tranquil interior, it's worth pausing at the front door, where the original vestibule still greets visiting guests.

Built of curving marble, brass, and glass, the unusual structure served as an airlock — a buffer against the cold in a home warmed by 14 fireplaces.

The vestibule now helps keep in the central air conditioning, a much later and controversial addition.

(In 2006, a next-door neighbor, "Sweet Caroline" singer Neil Diamond, claimed in a $2 million lawsuit that a new rooftop cooling unit illegally added 13 feet to the height of the building, obstructing his terrace views. The case settled for an undisclosed sum in 2010.)

The home's story begins with Wall Street stockbroker Elias Asiel, who purchased 15 East 63rd Street in 1885 as a new Victorian brownstone.

Asiel had grander plans. He hired one of the top architects of the day, John H. Duncan, to reimagine the 25-foot-wide property as a limestone-clad townhouse to rival any on the nearby stretch of Fifth Avenue known as "Millionaires' Row."

Duncan had just finished the General Grant National Memorial — a mausoleum for the 17th president and Civil War hero, overlooking the Hudson River — when he went to work for Asiel in 1897.

Entering Duncan's Beaux-Arts beauty, guests can cross a 46-foot, marble-tiled gallery to an oval-shaped dining room, or climb a sweeping, curved staircase to the parlor level.

The dining room, enclosed by pocket doors, mirrors, and fading, carved wood paneling, played a role in a 1906 break-in that left Asiel bloodied and bereft of his silverware.

The pre-dawn, gunpoint robbery was front-page news. "Elias Asiel Pounded Insensible with Brass Knuckles in Bedroom," blared a headline in the evening edition of the Sun.

According to accounts in four city newspapers, the two robbers broke into the basement service door using a saw and a diamond glass-cutting blade.

Awakened upstairs in bed, Asiel was no easy mark.

He got in a good punch or two before being beaten with brass knuckles and bound at the wrists and ankles "with stout pieces of cord."

He also refused to give up the combination to his safe, which contained "a fortune in gems" — heirloom jewelry he would bequeath to his daughter, asleep one floor up.

The robbers pocketed Asiel's $250 gold watch, 12 of his pearl-and-sapphire scarf pins, and $90 in cash. They then headed back downstairs to the dining room, where they'd left Asiel's silver in a pile to grab on the way out.

The two managed to pack up just three dozen forks and four dozen spoons when they were interrupted. Wriggling free of his ties, Asiel had pulled a bedside bell cord to wake the seven sleeping servants and was shouting for help out the window.

The thieves fled into nearby Central Park, leaving most of the silver on the dining room sideboard. They were caught and convicted some two years later.

The property's two most exquisite spaces — a wood-clad library and a bright drawing room — are at either end of the second level, the "parlor floor," where the ceilings are 17 feet high.

The wood and marble-clad library faces the front of the building, its two tall arching windows overlooking leafy East 63rd Street.

Photos of the library show no bookshelves. But there is reading material, if you're a cherub.

Pairs of the erudite tykes roost in each corner of the elaborately coffered ceiling, holding scrolls enscribed in Latin.

"Malo Esse Quam Videri," reads one, paraphrasing Cicero — "I would rather be than seem."

The second-floor drawing room is a bright sanctuary where sunlight from the terrace floods inside through two French doors and alights mirror to mirror.

A profusion of plasterwork decorates the ceiling and walls, ringing the space in garlands of budding and full-flower blooms.

The effect is like standing atop a wedding cake, under a rose bower, and enclosed by a house of mirrors all at once.

"Elegance upon elegance upon elegance," Louise Beit, the property's previous broker, enthused of the drawing room, in a YouTube tour of the home last year.

A spacious gallery connects the second floor's library and drawing room.

"Standing here in the gallery, you can feel how they love lavish entertaining in the Gilded Age," said Beit, of Sotheby's International Realty.

"You can greet your guests at the top of the steps with a string quartet entertaining you from the balcony."

Asiel and his two children — his bejeweled daughter would marry a Bloomingdale — enjoyed the home through the nineteen-teens.

In 1920, a year after his retirement, the broker died at home at age 69, missing the stock market crash by nine years.

The robbery was his most lasting claim to fame. His obituary in The New York Times noted that he "gained high praise from the police for his coolness and bravery in a single-handed battle with two burglars."

City records show that in the '60s and '70s, the home was owned by a California development company and had been divided into seven rent-stabilized apartments.

In 1984, it was purchased by Peggy Nestor and Marianne Nestor Cassini, the designer's then-secret wife, then in their 40s.

The sisters spent the next 30 years taking out mortgages and loans, renovating, and running the designer's businesses — Oleg Cassini, Inc. and Cassini Parfums, Ltd.

Cassini died of complications from a stroke in 2006, at age 92.

According to court documents, mortgage debts and other liens mounted to more than $30 million as the two sisters battled for a decade in state and federal court to keep the home.

The pair ultimately lost their battle against a bankruptcy judge's final 2024 order that the home be sold to satisfy more than $30 million of Nestor's mortgage debts and liens.

Federal Marshals broke into the home and forcibly removed the sisters, now in their 80s, to enforce a court-ordered eviction.

"They put me on the street in a robe!" Cassini's widow told the judge last month.

"Enough, enough, enough — we're done," a frustrated-sounding Judge Michael E. Wiles told the protesting siblings in approving the sale at a Manhattan bankruptcy court hearing this month.

"It's in the court file, for heaven's sake," Wiles said, rejecting the pair's repeated claim that they remain co-owners and that rent-stabilization laws still bar their eviction from the now single-family property.

The new owner — named only as "15 East 63rd Street, LLC" in court papers — is now poised to inherit an architectural gem, rich in history and potential.

"It appears that it has been a significant number of years since the townhouse was last comprehensively renovated," Brown Harris Stevens broker Sami Hassoumi said in a court document last month.

The mystery buyer's architect estimates that fully renovating the home will cost $25 million and take three to four years, Hassoumi said.