Louis Comfort Tiffany's design for the Frederick Ayer Mansion in Boston (1899 -1901) was described by Tiffany expert Alice Cooney Frelinghuysen as the designer's "most lavish and unusual use of mosaic decoration in the domestic context." The residence is the sole surviving example of exterior ornamentation designed by Tiffany and is one of his most intact and complete interior designs. Mrs. Ayer gave recitals and theatrical performances in the main hall, which is dominated by a dramatic gold mosaic tile half-dome that provides exceptional acoustics. As the home of Ellen and Frederick Ayer, who made his wealth in patent medicines, textiles, railroads, and real estate, the mansion also has important associations with social, cultural and economic history at the beginning of the 20th century. Tremont Preservation Services prepared the National Historic Landmark Nomination for the Frederick Ayer Mansion.