TREASURED Perhaps the best-designed line in the building, apartment 6D is a gorgeous sun-filled and spacious home positioned in a well-run cooperative located in an ultra-desirable location. The D line is the only one in the building that has a completely separate bedroom area with a door separating the living room, dining room, and kitchen from the bedrooms. The living room and formal dining room are most inviting - effectively a great room with a wall of windows overlooking a postcard worthy collection of red brick brownstones.  In addition to these soothing views, there are beautiful and generous built-ins, and a classic entrance hall giving the two rooms both an exciting and calming effect. The fully renovated windowed kitchen opens into the living/dining rooms, and enjoys the wonderful light streaming into the entire apartment. The kitchen features all stainless steel appliances including Bosch and Liehberr, as well as granite counters and slate floors.  Moreover - capping it all - there is a washer/dryer. In the master bedroom you will find extensive built-in storage and lighting, and the same seductive exposure north to red brick brownstones The second bedroom has bright southern exposure, also with generous proportions. The beautiful powder room and full bath are side by side through the hall that is privately enclosed behind a glass-paneled door. Overall storage is impressive.  Lavish original pre-war details accent throughout - box ceilings, transoms and moldings.  This is a well-run and appointed boutique co-operative.  It offers free cage and bike storage, a laundry room, and a great beautiful garden.  It has a live-in super.  The location cannot be matched - adjacent to the West 74th Street Historic District, and is incredibly convenient - a block from Fairway, sharing a street with Levain Bakery, short walks to both Central and Riverside Parks as well as museums, great restaurants, etc.  It is ensconced in as charming a part of the Upper West Side as one can hope to settle in.