The Andrew Carnegie Mansion is located at 2 East 91st Street at Fifth Avenue in Manhattan, New York City, New York. Andrew Carnegie built his mansion in 1901 and lived there until his death in 1919; his wife, Louise, lived there until her death in 1946. The building is now the Cooper-Hewitt, National Design Museum, part of the Smithsonian Institution. The surrounding neighborhood on Manhattan's Upper East Side has come to be called Carnegie Hill. The mansion was named a National Historic Landmark in 1966. The Gilded Age mansions were built in the United States in a short historic period spanning between the 1870s until about 1900. Raised by the nation's industrial, financial and commercial elite who amassed great fortunes coinciding with an era of expansion of the railroads, steel and fossil fuels industries, economic, technical and scientific progress, and a complete lack of personal income tax. This made possible the very rich to build mansions designed by prominent architects of its day and decorated with antiquities, furnitures, collectibles and works of art, many imported from Europe. Photographed by Detroit Publishing Company, 1903.