Horatio Gates Onderdonk House is a historic home located at Manhasset in Nassau County, New York. It was built in 1836 and is a Greek Revival style building with a two story, three bay central mass flanked by one story, one bay wings. It features a giant portico supported by four Doric order columns. By 1933, the Onderdonk farm was purchased for development by Levitt and Sons, who built the neighboring North Strathmore community. The house served as an office facility for the development, until the formation of the Strathmore Association, a membership organization composed of the owners of Strathmore property. The house and four corner plots adjoining “The Circle” were conveyed to the association on December 3, 1936, and the property has been maintained by the Strathmore Association since