High Quality Content by WIKIPEDIA articles! The Cedarmere-Clayton Estates are located in Roslyn Harbor, New York, United States, listed jointly on the National Register of Historic Places in 1986. Cedarmere, the smaller of the two, is William Cullen Bryant`s estate, located on the west side of Bryant Avenue overlooking Hempstead Harbor, now a historic house museum open to the public. Clayton, the bulk of the property, is the large landscaped Bryce/Frick estate, now home to the Nassau County Museum of Art. The two combined properties, with input from several notable architects, illustrate the development of estates on the North Shore of Long Island over a period of nearly a century.