The Stoneleigh Park Historic District  was listed on the National Register of Historic Places in 1988.
Stoneleigh Park is an early twentieth century upper middle class planned residential neighborhood of thirty single-family houses on approximately twenty acres of parklike property. Twenty-nine of the houses are situated on a looped drive that runs diagonally across the property. The remaining house, which was originally the home of C.B. Tremaine, one of the park's founder-developers, is located northeast of the entrance to the park on Dorian Road.
The entrance to Stoneleigh Park, near the corner of Westfield Avenue, is diagonally opposite the site of H.B. Tremaine's home (demolished) and adjacent to C.B. Tremaine's home (505 Dorian Road, formerly known as 1 Stoneleigh Park). Paired massive brick posts, with concrete ball finials that flank the roadway, mark the entrance. Each has a large, octagonal, iron lantern with an "S" for Stoneleigh and an iron ring for the chain, no longer present, which was formerly used to close the entrance on occasion. Slate sidewalks run between the main gateposts and smaller similar posts, without lamps, located to the outside of the larger ones. A second entrance at the opposite end of the park was closed in 1983 to discourage through traffic, which might disrupt the park's tranquility; however, there were no gateposts at that entrance.
The macadam roadway is approximately 25' wide and is lined on both sides with mature sycamores. The original slate walk encircles the loop. Twenty-two of the houses within the park are situated facing inward toward a center island created by the looping roadway. The remaining seven houses occupy the island, facing outward. The park is lighted by carriage-type lamps placed on simple wooden posts (replacements for original globes on low brick posts). All wiring is underground. When Stoneleigh Park was developed, the land was graded to create a park-like setting. Houses were placed at least 40 feet back from the road in compliance with a restriction in the deeds. Some of the structures sit on slightly raised lots. Most properties are well landscaped with a variety of shrubs and trees. Due to additional deed restrictions, there are no fences that can be seen from the street and little demarcation of property lines by means of plantings. It was the intention of Stoneleigh's developers to create a park setting that all residents could enjoy. The irregularly shaped lots of at least 100' x 200' are significantly larger than those in the immediate vicinity outside the park, thereby accentuating the park-like atmosphere.
Architecturally, the houses in Stoneleigh Park represent three periods of development. It was the Tremaine's intention that all houses should be variations of the Colonial Revival style, and the ten earliest or original structures are 2-1/2 story variations of that style, which date from the first decade of the park's existence. All display superior workmanship and are among the finest examples of the period in Westfield.
The second group, all constructed in the 1920's, also represent the Colonial Revival style, with the exception of several built in the English Tudor style. Although some of the houses are of the same size and scale as the original group, others are slightly smaller in scale and more typical of the period in which they were constructed.
The last group, if it can be termed such at all, consists of just four houses in contemporary and Colonial Revival styles, erected in the 1940's and 1950's as infill on the remaining undeveloped lots. Stoneleigh Park is now completely developed.
Most of Stoneleigh Park's houses are unaltered or, with the exception of one, insignificantly altered. They have retained their original siding and architectural detail and remain excellent examples of suburban upper middle class housing of the early twentieth century.
Stoneleigh Park (ca. 1904) is a fine example of a small, picturesque, upper middle class residential development of the early twentieth century. Planned by H.B. Tremaine, president of the Aeolian Company, and his cousin, C.M. Tremaine, it was designed to take advantage of the natural beauty of the site and to preserve a peaceful suburban setting for the homeowners, who were commuting New York executives and affluent Westfield businessmen and civic leaders. Stoneleigh Park continues to reflect the social and economic prominence of its original homeowners, as well as the town's commitment to the upper middle class lifestyle.