Library Days: 910 Park Ave., #10S Between 79th and 80th streets

This six-room Upper East Side apartment has a walnut-paneled library with builtins, a wet bar, and hidden storage. About 2,165 square feet, this corner co-op has three exposures and overlooks Park Avenue. The layout includes a private elevator landing, marble and onyx gallery, a living room, dining room, kitchen (with a washer/dryer), master suite (with a white marble bath and two walk-in closets), and second bedroom. This home also features original inlaid herringbone floors, panel moldings, and nine-plus-foot ceilings. Fitted with central air conditioning, it is in a full-service doorman building with a gym and private storage.

$4.5 million
Maintenance: $5,002
Broker: MacRae Parker/Brown Harris Stevens