Lyndhurst’s vast collection of art, antiques, and furniture have remained largely intact due to the mansion’s use primarily as a country residence. In most instances, the furnishings are original to the house, and more than fifty pieces were designed by the architect himself, Alexander Jackson Davis. The arrangement of the rooms reflects the lives of one of the three major families and the five major owners that lived here. As such, the mansion reflects the development of American identity and taste during the 19th and early 20th centuries.

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The grounds at Lyndhurst survive as an outstanding example of 19th-century landscape design. Elements include sweeping lawns accented with shrubs and specimen trees, the curving entrance drive revealing “surprise” views, the angular repetition of the Gothic roofline in the evergreens, and the nation’s first steel-framed conservatory. The rose garden and fernery are later additions.