The present home at the northeast corner of Thirty-ninth Street was built in 1879-1880 at a cost of four hundred thousand dollars.

The building is in Queen Anne style, of Baltimore pressed brick, with brown-stone trimmings, the interior decorations are the work of John La Farge, Louis Tiffany, and Franklin Smith, and the club's art collection includes Carpenter's Inauguration of Lincoln.

The long room on the first floor facing Fifth Avenue, from the windows of which at any hour of the day may be seen comfortable-looking gentlemen blandly surveying the passing procession, is the Reading Room, decorated in Pompeian style.
On the corner above where the Union League now stands there was, in 1854, a small country tavern known as the Croton Cottage.

It took its name from the Croton Reservoir, a block above, then on the other side of the Avenue.

A yellow, wooden structure, with a veranda reached by deep stoops from the sidewalk, and surrounded by trees and shrubbery, it flourished by vending ice cream and other refreshment to those who came to view the city from the top of the Reservoir walls.