Arguably the most extraordinary home in one of Park Avenue's most desirable Rosario Candela-designed Cooperative buildings - 778 Park Avenue - this full-floor, over 6,350sf simplex boasts exceptional scale, proportions, and flow with nearly 100 feet of frontage on Park Avenue through oversized windows, many of which are unique in that they extend low to the floor with Juliette-style balconies. A private elevator vestibule opens into the grand gallery, over 36 feet in length. Superb marble and fabric-clad walls with intricate passementerie detailing, and centuries-old imported Mahogany doors, make for a beguiling first impression of this home originally designed by Renzo Mongiardino. The elegant 32-foot salon/living room is anchored by a spectacular fireplace with one of several collector-grade imported mantels. French Doors reveal the formal dining room to the north, which could easily accommodate 20 people, a symphony of marquetry wood paneling that defies words, also with a fireplace and corner exposures. The adjacent butler's pantry with ample storage leads to the chef's kitchen, beautifully milled with professional-grade appliances. To the south is a charming library with a third fireplace. Next door, accessed via another pair of French doors, is an atelier housing artifacts that once housed an additional bedroom - easily restored - overlooking Park Avenue. The enormous bedroom wing is currently set up to house the Primary Bedroom Suite and two additional bedrooms, but this originally accommodated six bedrooms in total. The Primary Suite is both gracious and spacious: an entry foyer leads to the southwest corner bedroom. A regal wood-panelled bathroom is at one end, while a second marble bathroom is positioned at the other end, separated by vast closets and a dressing room with a make-up area. Forty-two windows fill this home with natural light all day with open views from all four exposures. Gleaming hardwood parquet floors, almost 11-foot ceilings, detailed lighting systems, and beautifully crafted custom moldings feature throughout. The Staff Wing, located off the service hall, includes a windowed laundry room, three staff rooms/home office/gym, and two additional bathrooms. Built in 1931, 778 Park Avenue is a full-service white-glove building, perfectly positioned just one block from the retail delights of Madison Avenue and two blocks to Central Park and Museum Mile, and consists of just 18 homes over 18 floors. The building recently added a large, professionally equipped fitness center with natural daylight and an adjoining make-up/hair room. It has a full-time live-in superintendent, bicycle storage, and is pet-friendly. There is a 3% Flip Tax paid by the purchaser and an assessment of $7,975/month till the end of 2026.