The legendary Downtown financial street is fast becoming residential In the mid-1990s, soon after Donald J. Trump bought the towering 40 Wall Street, he was spending time with “a great French fashion designer,” who was unaware of the Donald’s purchase. As Trump recalled the discussion some years ago, the designer told him, “The place I would most want to live is Wall Street: it’s the most beautiful and most romantic place in the city.” While Trump previously ensured the 70-story 40 Wall Street has the legal ability to convert to residential condominiums, he now has no plans to do so. Oddly enough, that’s because 40 Wall could remain one of the few remaining office properties along Wall Street, thus driving up its value even more. Up and down the hallowed capital-intensive canyons, building after building is getting a facelift inside and out, and turning into modern, luxury apartments selling for nearly $1,000 a foot. …Under the city’s 421g program, residential conversions with up to 25 percent commercial space have various real estate tax abatements and exemptions for as long as 14 years. But owners and investors say that benefit is not just driving the conversion to rental fever – it’s just a nice bonus on top of the sell-out value of condominiums. “A lot of jobs were going to be rentals but when you ran the numbers they all converted,” said Andrew Heiberger, president of Citi Habitats, which provides rental and marketing services. From east to west, Wall Street is turning to Sleep Street…