343 Sixth Avenue #4

343 Sixth Avenue went up in 1920 as a four-story brick apartment house on the corner of 4th Street, one of the ordinary multifamily buildings absorbed into the rowhouse grid of central Park Slope. For most of a century it held eight modest apartments. It was never a trophy. It was infrastructure.

Around 2016, DNA Development and Phasa Development restacked it into something the neighborhood almost never produces: a five-unit condominium with one full-floor home per upper story, two duplexes at the base, and an elevator that opens directly into each residence. The developers added a common roof deck with sightlines to the Statue of Liberty, New York Harbor and the Manhattan skyline, along with private storage, a bike room and tilt-and-turn windows. The pitch, in effect, was brownstone scale without the brownstone stairs.

The market did not take long to accept the argument. The penthouse was listed on June 10, 2026 and signed a contract on July 2, roughly three weeks later.

Unit 4 is the penthouse, and the penthouse is the entire top floor: 2,165 square feet holding three bedrooms, a den and three baths, with corner exposures pulling light down both Sixth Avenue and 4th Street. There is no shared hallway to pass through. The elevator ride ends inside the apartment.

The listing describes a great room 28 feet across, anchored by a gas fireplace, with white oak herringbone floors running through the plan, a kitchen fitted with Wolf and Sub-Zero, and radiant heat under the primary bath floor. That is the full-floor logic at work: with no neighbor beside you, the living space can stretch the whole width of the building.

The upper level is the real argument. A private rooftop terrace, which the listing measures at 800 square feet and describes as planted with flowering trees and equipped with an outdoor kitchen, sits above the apartment with the harbor and the skyline in view. In a neighborhood where outdoor space usually means a garden four flights down, a full garden on the roof reverses the equation.

The corner of Sixth Avenue and 4th Street is mid-Slope at its most legible: rowhouse blocks, corner retail, the avenue running quiet between them. Two short blocks west is Washington Park and the Old Stone House, the reconstructed 1699 Vechte-Cortelyou farmhouse where the Maryland 400 made their stand in the Battle of Brooklyn in 1776. It is one of the few places in the city where the ground itself carries the founding record.

The listing team is unusually rooted in that record. Co-listing broker Charlie Pigott sits on the board of the Old Stone House, is a fourth-generation Park Sloper whose family has been in the neighborhood since the late 1800s, spent a decade on Community Board 6 and has 38 years in the business. Nathalie Roy, the primary agent, is Quebec-born, more than twenty years a Brooklynite, and once ran A Brooklyn Table, a housewares shop on Atlantic Avenue. Few listings come with this much local memory attached.