The Frederick Ayer Mansion is a National Historic Landmark on 395 Commonwealth Avenue in the Back Bay neighborhood of Boston, Massachusetts.

The mansion was the home of Frederick Ayer, owner of the American Woolen Company, and features well preserved design work by Louis Comfort Tiffany.

[1] The Ayer Mansion was built in 1900, designed by Louis Comfort Tiffany in a partnership with Alfred J. Manning.

The Trimount Foundation and Bayridge Residence and Cultural Center, affiliates of the Roman Catholic Opus Dei organization, purchased the Ayer mansion and adjacent buildings in 1964.

They are currently operated as private residential facilities for area college students, although tours are occasionally given of the public spaces where Tiffany-designed elements have been preserved.