In 2009, former Morgan Stanley CEO John Mack paid $13.5 million for a Manhattan carriage house; after transforming it into a nearly 16,000-sq-ft mansion, it is now listed for $80 million

Former Morgan Stanley CEO John Mack and his wife Christy have put their Upper East Side abode on the market for a whopping $80M, making it the most expensive townhouse currently on sale in New York City. If sold at the listed price, the deal would break the city’s townhouse record, previously set in June 2019 when 14 East 67th Street, a 22,000-square-foot mansion, was sold for $77.1 million.The couple bought the abode in the form of a 33-foot-wide building that had never been a home at all. Located at 165 East 70th Street, they scooped it up for $13.5 million in 2009, according to property records, back when Mack was a Wall Street giant, working at Morgan Stanley as the CEO. The building actually dates to 1902, when society architect C.P.H. Gilbert, the mind behind some of Fifth Avenue’s grandest mansions, designed it for banker Henri P. Wertheim.In a following six-year gut job, the couple kept the landmarked limestone facade, added a floor and reinforced the guts with steel beams, transforming it into a roughly 16,000-square-foot mansion with 20 rooms. The Macks had hunted for roughly a decade for a move-in-ready townhouse before settling on building their own, said listing agent Mike Fabbri of The Agency to The Post. Now the couple is cashing out and retiring to North Carolina, where they both grew up.The home is a secured fortress. It has a state-of-the-art alarm system, dedicated security offices and even a bulletproof front door. A snowmelt system keeps the sidewalk clear in the winter. “So when it snows outside, the sidewalk in front of the house melts away the snow,” Fabbri explained. Inside, heat runs everywhere. “Not just the bedrooms and the baths, like every single floor is heated,” he said.The cellar works as a private wellness club with a hot tub, cold plunge, steam room, sauna and massage room. There’s a 13-seat screening room, a wine cellar for 6,319 bottles, two elevators (one of them high-speed), six wood-burning fireplaces and three landscaped terraces, including a 480-square-foot perch on the roof. Other highlights include a wood-panelled library, two soundproof offices, a full gym and private guest quarters with a full kitchen and a chef’s kitchen with a walk-out dining terrace. There is also a private curb cut leading to a garage that doubles as a party space. “You’re usually giving up something to live in a townhouse,” Fabbri said. “You’ve got it all in this house.”Previously, only five people have owned the site, according to Fabbri. Singer sewing machine heir Stephen C. Clark used it as a garage and chauffeur’s quarters while Paul and Bunny Mellon, used it as a private garage before selling it to the Macks.“It’s completely turnkey, which is the magic word,” Fabbri said while highlighting that the new owner would not have to lift a finger to make the house comfortable and luxurious. “It’s not just a showpiece, which it is. It’s also somewhere that’s really functional.”