21 E 90Th St

Built in 1927 and rising 14 stories with just 18 units, this is a refined full-service prewar cooperative on a picturesque Carnegie Hill park block. Designed by George F. Pelham, the masonry building preserves traditional prewar proportions: high beamed ceilings, detailed millwork, and semi-private elevator landings that open to gracious entrance foyers. Apartments range from classic five- and six-room layouts to expansive duplex penthouses with wraparound planted terraces and private elevator landings. Interiors commonly feature formal dining rooms, eat-in kitchens, wood-burning fireplaces (some converted to gas), abundant built-in shelving, walk-in closets, hardwood floors, and pantry or staff rooms; many homes have washer/dryers and restored period hardware alongside modernized kitchens and baths. Shared building services include a full-time doorman, live-in superintendent, bike room, individual basement storage, complimentary laundry, a small fitness room, and a recently renovated lobby and package room. Exterior offerings are limited to private outdoor terraces under 60 sq ft on select units and access to a planted courtyard; there is no on-site garage. The co-op is pet- and pied-a-terre–friendly with typical board approvals, allows up to 50% financing, and charges a 2% flip tax. Located half a block from Central Park’s Engineers’ Gate and the Jacqueline Kennedy Onassis Reservoir, it sits amid Museum Mile, boutique shopping, and established private schools, delivering an Upper East Side lifestyle centered on culture, parks, and quietly elegant prewar living.