Exclusive | A rare penthouse with one of NYC’s few golden domes has hit the market for $13.5M 

You can now call a dome your home.

A Chelsea penthouse now on the market for $13.5 million is offering house hunters something quite rare: one of just three residential cupolas in all of New York City — a gold-coated dome perched high above Sixth Avenue, The Post has learned. 

Set atop the landmarked O’Neill Building at 665 Sixth Ave., the duplex spans roughly 4,800 square feet, with an additional 2,500-plus square feet of private outdoor space — a combination that’s nearly as scarce as the dome itself. 

Inside, the home is anchored by a 53-foot-long great room lined with more than 220 feet of windows and bathed in southern and eastern light.

But it’s the dome — a soaring, circular structure rising nearly 43 feet — that steals the show.

“The building was constructed in 1887 and it was a ladies’ mill, a department store,” listing broker Peter Ocean, of Serhant, told The Post. “And so when they built this, they had the two cupolas.”

Today, that historic feature has been reimagined as a livable space, currently set up as a home office but flexible enough to serve as a media room, a lounge or a private retreat.

“It’s a decent room that you can sort of imagine turning it into doing whatever you want,” Ocean said. “It’s large enough for that.”

“There are only three apartments in the city, including this [penthouse] which have cupolas, and this one is the most recognizable of them all,” Ocean said.

The scarcity extends well beyond New York.

“There’s literally only a handful in America,” he added. “I think it was below five.”

The O’Neill Building dates back to 1887, when it served as a flagship dry goods emporium catering to well-heeled shoppers along Sixth Avenue’s Ladies’ Mile. Its signature domes originally functioned as architectural billboards — gleaming markers of prestige designed to draw attention from blocks away, including riders on the now-defunct elevated train line that once ran past its oversized display windows.

Those domes disappeared in the early 20th century, only to be painstakingly reconstructed during a 2005 condominium conversion. 

With original plans lost, architects relied on archival imagery to recreate the structures, finishing them in gold leaf while adapting them for modern residential use.

Inside the penthouse, the layout is currently configured as a three-bedroom, though it was designed to accommodate four. The upper level is devoted to a primary suite with a spa-style bath, dual dressing rooms and direct access to one of three terraces that wrap the residence.

The kitchen, outfitted with high-end appliances and a butler’s pantry, is geared toward entertaining — something the home does particularly well thanks to its expansive outdoor footprint.

“I challenge anyone to find an apartment that has 2,500 square foot of outdoor space. I mean, it’s insane,” Ocean said.

The terraces offer a rare level of privacy for the neighborhood, surrounded largely by commercial buildings that quiet down after business hours, while also providing ample room for large-scale gatherings. But it also offers the most idyllic view of the dome-like structure itself. 

“You are able to host,150, 200 people there easily,” he added.

The current owner, who has held the penthouse since 2008, is now looking to downsize after years in the sprawling space.

“The house is just so large for one person,” Ocean said, noting that the owner’s children have since moved out. “I think she’s come to a point now where she has decided … I want something a little bit smaller.”

As for the next buyer, the property’s appeal cuts across categories — from families seeking townhouse-scale living in a full-service building to creatives or social buyers drawn to its one-of-a-kind design.

“It is going to be someone that is just in love with outdoor space, and that sort of home feel,” Ocean said. “And then we have sort of the creatives … just looking for really, really cool space.”

Ultimately, the listing hinges on a combination that’s difficult to replicate — historic pedigree, massive outdoor living and a skyline-defining architectural feature.

“It’s got that double rarity,” Ocean said. “It’ll be hard for anyone to find something like this.”