For the first time in more than 50 years, this apartment is back on the market — and it still looks as young as ever.

Unit #4/5B at 322 E. 57th St. has not changed hands in over half a century, and now this two-story glory is listed by Brown Harris Stevens’ Maria Serena Torresy and Julianna Simmons for $3.5 million.

“The building is considered one of the finest prewar buildings in New York City and its had a very illustrious past of shareholders,” Torresy, who has lived in the building since 1970 (and at one point owned five floors of it), told The Post. 

Each one of the 22-story building’s 18 co-op apartments is a duplex, save only for the penthouse unit, which is a triplex.

“The owner of the apartment that is on the market was a renowned neurosurgeon,” Torresy said, adding that it is an estate sale. 

The late neurosurgeon’s apartment offers the same distinctive building features that can be found in every unit in the building: A living room with double height ceilings — “They’re soaring” at approximately 18- to 19-feet tall, said Torresy — 14-foot windows, generous floor plans and “spectacular light.”

The unit also has a wood-burning fireplace, a solarium, a formal dining room and three bathrooms. Listing photos also show a modern, floating staircase leading to the upper level, a cozy, brick-floored kitchen, a millwork-detail filled bedroom with built-in bookshelves and multiple stained glass windows.

The property, built in 1929, also features an elevator, a doorman, basement laundry and additional storage. Pets are allowed.

Notable past building residents include Art Deco painter Tamara de Lempicka, actress Lily Pons and her husband, conductor Andre Kostelanetz — and the owner and namesake of the high-end Chinese restaurant and local institution Mr. Chow, located just next door. Orson Welles, added Torresy, is also reputed to have lived at the address, although “no one can confirm that.”