The Boston Post Road Historic District is a 286-acre (116 ha) National Historic Landmark District in Rye, New York, and is composed of five distinct and adjacent properties. Within this landmarked area are three architecturally significant, pre-Civil War mansions and their grounds; a 10,000-year-old Paleo-Indian site and viewshed; a private cemetery, and a nature preserve. It is one of only 11 National Historic Landmark Districts in New York State and the only National Historic Landmark District in Westchester County. It touches on the south side of the nation's oldest road, the Boston Post Road (US 1), which extends through Rye. A sandstone Westchester Turnpike marker "24", inspired by Benjamin Franklin's original mile marker system, is set into a wall that denotes the perimeter of three