Alexander McMillan Welch (1869-1943) was a New York City based architect who practiced independently and as a member of Welch, Smith & Provot. His firm was best known for designing New York City townhouses in the Beaux-Arts style. The collection includes 1,641 architectural drawings, 196 student drawings, 14 student notebooks, 99 loose photographs and 3 photo albums of project photography, project specifications and files, and some professional ephemera.

Architectural plans and renderings of Welch's designs, largely New York City residences, circa 1890s-1920s; specifications; photographs; and brochures advertising buildings at 787 Fifth Ave., 628 Fifth Ave., and 71 and 73 Murray Street, in New York City. Drawings and a sketchbook done by Welch while a student; fourteen notebooks containing Welch's notes from Columbia classes in architecture, 1888-1890; licenses to practice in New York and New Jersey, 1904-1923; a certificate, 1937, and related correspondence relating to Welch's appointment as a U.S. delegate to the fourteenth International Congress of Architects, held in Paris, July 18-25, 1937. A list of U.S. delegates is included. Of note are drawings and papers for the restoration of the Dyckman House, an 18th century farmhouse in upper Manhattan (1910-1917); and the Mrs. Rutherford Stuyvesant Estate in Allamuchy, New Jersey, and the Rutherford Stuyvesant Momument in Tranquility Cemetery, Tranquility, New Jersey, designed by sculptor Daniel Chester French.

Included are approx. 7,000 architectural drawings, circa 1910s-1940s, for projects designed by Delano & Aldrich, including La Guardia Airport in New York; several buildings at Yale University; Willard Straight Hall at Cornell University; various buildings at United States Military Academy at West Point; the National Gallery of Art in Washington, D.C.; alterations to the White House; numerous residences throughout the New York City metropolitan area, particulary the Dwight W. Morrow house in Englewood, N.J., the J.A. Burden house in Syosset, N.Y., and the Willard D. Straight house on East 92nd Street in New York City; and various schools, churches, and residential structures throughout the United States. Rendered competition drawings are included. Drawings made by William Adams Delano while a student at the Ecole des Beaux-Arts, Paris, circa 1900. Also, 6 boxes of photographs of Delano & Aldrich completed projects, chiefly residential structures.

Louis Henry Sullivan (1856-1924) was an American architect and partner in the Chicago architectural firm Alder & Sullivan. He is also known as a mentor to architect Frank Lloyd Wright. The core of the collection is made up of 122 drawings given to Frank Lloyd Wright by Louis Sullivan before Sullivan's death in 1924. The Avery collection represents the bulk of what remains of Sullivan's drawings. Most of the drawings in this collection are designs for ornament representing different stages of Sullivan's stylistic development. Some drawings are annotated by Wright. The collection also includes additional donations of drawings, objects, and papers collected over the years.

Paul Nelson was an American architect educated at the Ecole des Beaux-Arts in Paris and practicing in France and the United States. This collection contains materials related to Nelson's personal, professional, and academic lives, the bulk originating during his residency in the France, beginning in the 1920s.

Also, a variety of professional and personal miscellany, such as correspondence, clippings, pamphlets, flyers, postcards, invitations, menus, receipts, a diploma, caricatures of colleagues, and Sawyer's monocle

This collection contains architectural photographs, drawings and records related to the architectural projects and designs of Warren and Wetmore, principally in the United States, but also representing commissions in Canada, Cuba, and Puerto Rico. Unfortunately, the bulk of architectural drawings produced by the firm are no longer extant. Additionally, it holds a variety of photographs and other records used as reference materials in the course of Warren and Wetmore's professional work. Lastly, a small group of student and personal papers and photographs from Whitney Warren completes the collection.

Also, typescripts of lectures delivered by Boring in architecture courses at Columbia, 1932-1933, miscellaneous typescripts of articles and printed materials, 1930-1933, and a typescript of Boring's autobiography, MEMORIES OF THE LIFE AND WORK OF WILLIAM A. BORING, circa 1937. Also included are four sketches by Henri Gauthier, Edward Tilton, Maurice Sashin, and Joseph Laudin.