The "Eagle's Nest" mansion is unusual for estate architecture on Long Island because of its Spanish design, a style that is seldom seen in the region. The palatial, Spanish Revival style is actually less "Spanish" than it is a personal evocation of Vanderbilt's Mediterranean impressions as interpreted by his architects during a period of estate building that lasted over twenty-five years. With the requisite red tile roof, stucco facades and central courtyard, the ironwork by Samuel Yellin is the final element characterizing this style.
Two building campaigns followed the original construction of the house, transforming it into the extensive mansion complex that visitors see today. Each was prompted by incidents in Vanderbilt's life, the first by his inheritance of $21 million after his father's death in 1921 and subsequent marriage to Rosamund Warburton in 1927, and the second by the tragic death of his son Willie K. III in 1933. A visit to the "Eagle's Nest" mansion today provides visitors a glimpse at the life of William K. Vanderbilt II through the estate that memorializes his legacy.
The mansion was begun in 1910 as a modest bachelor's retreat, built at a comfortable distance from the legendary concentration of Gold Coast estates located closer to New York City. The original bungalow was perched high above Northport Harbor where a boathouse and wharf accommodated Vanderbilt's greatest passion, sailing. His other passion, motor car racing, is represented on the estate by the two-story automobile Garage [now the museum's Education Center] and by a large revolving turntable located on the lower level of the Memorial Wing, where Vanderbilt's custom built 1928 Lincoln touring car is displayed.