An unparalleled opportunity to acquire one of the Upper East Side's most storied and architecturally distinguished mansions, 45 East 78th Street is a landmarked townhouse of rare provenance, grand scale, and timeless elegance. For decades home to the celebrated Mnuchin Gallery, 45 East 78th Street now can present itself again as a private residence or commercial art gallery of the highest order. Six magnificent stories with private elevator service throughout, this 33' 4” wide mansion offers approximately 17,600 square feet of extraordinary volume across meticulously proportioned floors. Every detail speaks to a grandeur that is increasingly impossible to find in New York City. Guests enter on the first floor into a beautiful and gracious entry gallery - a statement of arrival that immediately sets the tone. Adjacent to the double-door entry is what can be an elegant entertaining or dining gallery, perfect for large-scale receptions or intimate dinners. The kitchen on this level connects seamlessly to the floors above via a private staircase, which can facilitate entertaining. The parlor floor is the social heart of this residence. Here, a dramatic circular staircase - a sculptural centerpiece - anchors a floor of sweeping, light-filled spaces. Two large formal entertaining spaces command each end of the property, each with fireplaces. These rooms, with their soaring ceilings and landmarked architectural detailing, are simply irreplaceable in today's market. The entire third and fourth floors present well-proportioned rooms, offering flexibility for your desired use. Throughout the home, four full bathrooms and five powder rooms serve each floor with ease and discretion. The crown of this exceptional residence is a 1,335-square-foot private rooftop terrace - a sky-high sanctuary above the Upper East Side roofline with direct elevator access. This floor is equipped with a full guest suite including a bedroom, kitchenette and full bathroom. The garden level offers tall ceilings and oversized windows overlooking a north-facing courtyard. The mansion dates to the early 1900s and, as a designated landmark, has retained its grand yet domestic character. Situated on East 78th Street between Madison and Park Avenues, the address places residents moments from Central Park, world-class museums, and the finest restaurants and boutiques the Upper East Side has to offer. A property of this caliber comes to market once in a lifetime.