Styles and design
Gaetan (Gaetano) Ajello is best known for his architecturally significant apartment houses located on Manhattan’s Upper West Side. Ajello designed thirty-eight apartment houses during his twenty-year career, and while most of them have survived intact, some have been altered.
He engaged in both Renaissance architecture and Neoclassical architecture styles, but he consistently used limestone and terracotta. He also often included Tiffany-style windowed lobbies in his designs.
Ajello also often designed lobbies that would shield from first view the elevators, presenting instead a staircase with a curved balustrade in order to recreate the experience of entering a single-family home.
In 1912, Architecture and Building  devoted an entire article to his architecture. The piece included photographs and plans of nine apartment houses. This same year, Ajello began working for the Paterno and Campagna families, two of the most influential apartment developers of their day. According to the New York City Landmarks Preservation Commission, Ajello’s last known commission was 395 Riverside Drive, a $2 million project, completed in the mid-1920s.
He gave Rosario Candela, a fellow Sicilian, his first architectural job.
Awards and recognition
In 2006, the Claremont Theater, in the Manhattanville neighborhood of New York City, Ajello’s only known non-residential work, was designated as a Landmark by the New York Landmarks Preservation Commission. Thomas Edison once shot a short film in 1915 featuring the building's entrance 
- Office for Metropolitan History, The Building Permits Database, 1900-1986
- Gray, Christopher (February 6, 2009). "For a Grande Dame, More Than an Eye-Lift". New York Times.
- Gray, Christopher (June 11, 2006). "Remembering an Architect Who Shaped the West Side". New York Times.
- Photos of engraved cornerstones on the Upper West Side
- Starrett, Theodore (December 1912). "John Wellborn Root". Architecture and Building 44 (11).
- Grace, Matthew, "New Landmark Designation: Claremont Theater" at the Wayback Machine (archived July 26, 2006), The New York Observer, June 7, 2006.
- "Claremont Theatre: NY 1915 Thomas Edison", Library of Congress, film archives. (MPG version)
- "Claremont Theater Building, 3320-3338 Broadway (aka 536-540 West 135th Street), Manhattan", New York City Landmarks Preservation Commission, June 6, 2006, Designation List 375 LP-2198
- Remembering an Architect Who Shaped the West Side - The New York Times
- Streetscapes: For a Grande Dame, More Than an Eye-Lift - The New York Times
- Architecture and Building, December 1912
- Full listing of Ajello's Manhattan works
- Article about Ajello's 1912 Renaissance-style Lucania, at 235 West 71st Street
- Manhattan Valley neighborhood history