The Fifth Avenue aerie that sat for more than 500 days finally found a buyer — and the markdown is brutal.

A 40-foot golden dome. Views of the Empire State Building from a private roof deck. A front-row seat next to the Flatiron Building. None of it was enough to land a buyer at $25 million.

The five-bedroom, 4.5-bathroom penthouse atop the Sohmer Piano Building at 170 Fifth Ave. has sold for $9 million, The Post has learned. 

That marks a 64% drop from its November 2024 debut, and only a little more than the $7.2 million tech mogul Greg Carr paid for the raw space back in 2001.

The purchaser is keeping a low profile. Records list the buyer as White Piano LLC, an entity with an East 20th Street mailing address.

The price slide was steady. After hitting the market at $25 million, the two-floor home was cut to $14.9 million and lingered on the market for 530 days.

Rather than keep waiting, Carr handed the keys to Concierge Auctions, which projected opening bids between $6 million and $9 million. 

Bidding opened at $8.25 million after the reserve was met, and the hammer fell live July 29 at Sotheby’s New York. Concierge later announced the sale as pending at $10.147 million.

Listing broker Claire Groome of Sotheby’s said the traditional route had run its course.

“Auctions are really exciting, and people like doing them,” Groome said. “It’s the better way to move something that usually sits on the market otherwise.”

Carr built Boston Technology and once chaired Prodigy. He spent nearly 25 years hosting guests beneath the gilded cupola, and has said Lauren Bacall once danced there.

These days Carr’s attention sits half a world away. He has steered more than $100 million toward wildlife conservation at Gorongosa National Park in Mozambique, and every dollar from this sale goes to the Gorongosa Project.

He previously told The Post the home’s history was the draw from the start.

“What initially drew me to this penthouse was the fact that it represents an extraordinary chapter of New York City’s architectural history,” Carr told The Post. “From the moment I acquired it, we were committed to preserving its character while thoughtfully reimagining it for modern living.”

Carr has described the chapter in theatrical terms.

“If life is a three-act play, that was act two for me, and it was a magnificent act,” he has said. “I loved that place and got a lot of use out of it.”

The roughly 5,700-square-foot duplex comes with more than 40 oversized windows, an 80-foot greenhouse-style window expanse, two grand foyers joined by a circular limestone staircase and a privately deeded roof deck. The corner primary suite includes more than 35 linear feet of closet space and a spa bath with a Waterworks soaking tub.

Sotheby’s Lawrence Treglia, who co-listed the property with Groome, pitched it as more than a typical luxury apartment.

“Whether you’re entertaining beneath the golden dome, enjoying sunset views from the private roof deck or simply taking in the natural light that pours through the home’s expansive windows, every space feels connected to the energy and beauty of New York City,” Treglia said.

After the sale, Concierge Auctions CEO Chad Roffers framed the auction as the right tool for the job.

“The auction process delivered the competitive, time-defined environment this landmark property deserved,” Roffers said in a statement.