A full-floor dwelling at the prestigious 845 Fifth Ave. co-op is on sale for the first time in nearly 60 years, looking nearly untouched from that long-ago era.

The $30 million listing encompasses the entire second floor of the 17-unit building, plus a guest suite on the ground floor. But even better are its eye-catching interiors, which look frozen in amber.

The listing, held by Emanuele Fiore of Serhant, advertises a “mint, museum-quality condition,” with modern renovations whose listing images instantly transport viewers to a New York of years past.

Its ownership is tied to the late Alan “Ace” Greenberg, who for decades led the former financial powerhouse, Bear Stearns.

Greenberg, who died in 2014, led Bear Stearns as CEO from 1978 to 1993 and served as its Chairman from 1984 to 2001. He was survived by his second wife, Kathryn Olson Greenberg, and two children from his first marriage, Ted Greenberg and Lynne Koeppel.

Its not clear at press time who among his family is currently in ownership of the property.

Also known as 4 E. 66th St., the 126-year-old building designed by James E.R. Carpenter is one of Lenox Hill’s most sought-after addresses, filled with old-world grandeur and ideally located along Central Park. It’s the same co-op where Julia Koch purchased a $101 million spread in 2022 from the estate of late Microsoft co-founder Paul Allen.

The $30 million listing is its sole available home out of 17 units, according to StreetEasy. The five-bedroom home on the second floor spans roughly 7,500 square feet, which means there’s plenty of room for perks.

“I’ve never seen a dining room as large or as wide as this one,” Fiore told The Post. 

Though there have been upgrades, the home’s classical layout has remained largely untouched. Parquet de Versailles floors, custom paneling and original moldings line the home. ‘His’ and ‘Hers’ living rooms remain as well, with the former acting as a billiards and bar salon. Both expansive rooms overlook Central Park and feature woodburning fireplaces and marble mantels.

A custom chef’s kitchen opens to a breakfast room, and connects to a service wing accessed by a separate elevator entrance. The wing includes a pantry, a laundry room, a gym, four staff rooms and two full bathrooms.

The paneled library is the home’s most recently renovated space, Fiore said, and includes a discreet powder room. 

The home’s five bedrooms, one of which is used as an office, are tucked away. The corner primary suite enjoys its own woodburning fireplace, as well as two dressing rooms and marble-lined bathrooms. 

The wood-paneled guest suite on the ground floor is included in the purchase price. The studio space includes a Murphy bed, a full kitchen and a bathroom.

Fiore confirmed that the home was last purchased in the late 1960s, but declined to comment on the seller.

Due to the age of the transaction, a deed for No. 2 is absent from the city’s digital records.

The guest suite, however, was purchased in 2005, with records listing the Greenbergs as the buyers. The pair paid $600,000 for the additional space.