Warren & Wetmore, Architects
Whitney Warren [1864-1943] was a cousin of the Vanderbilts. After deciding to study architecture in 1883, he enrolled at Columbia University but stayed for only one year. In 1884, he left for Paris to attend the Ècole des Beaux Arts and remained for ten years, studying under Daumet and Girault. Warren returned to New York in 1894 and, with characteristic resourcefulness, convinced one of his first clients, a lawyer named Charles Wetmore [1867-1941], to become his partner. The new firm's bid for recognition came in 1899 when the New York Yacht Club [an organization familiar to William K. Vanderbilt, II] held a competition for a new clubhouse. Warren & Wetmore received the commission, and as a result, established their reputation in New York.
Almost immediately, the firm was engaged as architects for the New York Central, Michigan Central and Erie and Canadian Northern Railroads. They were responsible for the design of the entire Grand Central Terminal Group, which began with the design of the Grand Central Station [1903-1913] and ended with the New York Central Office Building . The complex included several Vanderbilt-financed hotels, among them the Vanderbilt , the Biltmore  and Hotel Commodore .
Considering these associations with the Vanderbilt family, it is reasonable to attribute the 1910 design of "Eagle's Nest" to Warren & Wetmore, although documentary evidence has yet to be found that confirms this attribution. Stylistically, the original buildings on the estate did resemble some of the early work that the firm produced on Long Island, such as the outbuildings for Clarence MacKay's "Harbor Hill" in Roslyn . In addition, although no records have been located for the first phase of the mansion's construction, later blueprints and drawings confirm that the firm was commissioned in various capacities from 1926 until 1930. During this period, Warren & Wetmore also designed the Deepdale Golf and Country Club in Great Neck  for William K. Vanderbilt II. It was also in the "Spanish" style.