Crowning London Clay Townhouse, The Penthouse Duplex is an architectural tour de force pairing the scale and grandeur of a multi-level private mansion with the privacy, sky-high outdoor living, and turnkey convenience of a premier downtown penthouse.Spanning two sun-drenched levels, this one-of-a-kind residence is illuminated by a breathtaking 20-foot central glass atrium that channels natural light deep into both floors. The lower level is anchored by a massive 26-foot-wide great room featuring soaring ceilings, architectural detailing, and an open layout tailored for grand living and fireside dining. The exhibition kitchen is appointed with custom millwork, sculptural stone surfaces, and professional-grade Sub-Zero and Wolf appliances.The private quarters are led by a primary suite of dramatic proportions, complete with custom walk-in dressing areas and a windowed five-fixture bath, with custom vanities, and finished in bookmatched stone and bespoke cabinetry. Two additional king-sized bedroom suites offer generous closet space, private en-suite baths, and bright exposures. A thoughtfully designed den provides an intimate retreat, offering a sense of privacy and tranquility.A true defining feature of the residence is its private exterior domain, offering 1,589 square feet of outdoor space across multiple levels, capped by a private rooftop terrace. Designed with dedicated areas for lounging, sunbathing, and open-air dining, this sky retreat commands panoramic skyline views over downtown Manhattan.As one of only three homes in a historic townhouse originally touched by master builder Robert Siegel, The Penthouse offers key-fob elevator access, a restored foyer with Apparatus fixtures and brass-inlaid tile, and an advanced 24-hour Virtual Doorman with package reception. Located at the intersection of Madison Square Park, Gramercy Park, and Flatiron's Michelin Row, The Penthouse is a trophy home of irreplaceable character, beauty and scale.