Lauded as "The Best House on the Best Block" by The New York Times, The Thomas Lamont mansion is extremely impressive in scale, architecturally significant, and supremely situated on one of the most coveted and loveliest tree-lined blocks on the Upper East Side.

Commissioned by Thomas W. Lamont, a partner at J. P. Morgan & Company, the renowned architecture firm of Walker & Gillette created a Tudor-revival mansion on the 55-foot wide mid-block lot. Anointed by many of New York's influential families, the firm is well-known for celebrated and important residential buildings, such as the Charles E. Mitchell House (now the French Consulate), the Henry P. Davison House (now the Italian Consulate), and the William Goadby Loew House (now the Spence School), as well as the Fuller Building and the East River Savings Bank.

The six-story landmarked mansion has had but two owners in its 100-year history: Thomas and Florence Lamont, and the Visiting Nurse Service, to which it was bequeathed by Mrs. Lamont upon her death in 1954.

Constructed in 1922, Walker & Gillette's fanciful and imaginative design incorporates leaded-glass windows, a cloistered side garden, planned irregular patterns of masonry work, and a picturesque roofline of grouped chimney flues. Gracefully set back from the street by ten feet, the house is visually resplendent. Charming detail abounds.

Inside, the house retains a few marvelous and significant original rooms, such as an oak-paneled library with an ornately-carved marble mantle, thirteen and a half-foot ceilings with carved plaster detail, and very tall leaded-glass windows. While these rooms have been preserved, and the house has been extremely well and maintained and updated to today's systems, much of the house has been converted to flexible and modern office space, most recently by Breyer Blinder Belle in 2009. Conveniences that have been overseen during the conversion include a hydraulic elevator and a water-cooled central air conditioning system with two chillers, each with four condensers.

At nearly 23,000 interior square feet and with over 2,500 square feet of outdoor space, the 50-foot wide building offers myriad possibilities.