All Names
- A.B. & W. Transit Company
- A.B. Mullett & Co. (90)
- A.M. Schneider & Co., Architects
- Abbe, Truman, 1873-1955 (2)
- Abel, Howard G., 1939-
- Abell, Arunah Shepherdson, 1806-1888
- Aber, Richard, 1948-
- Abrams, Trenholm (2)
- Adair, Herbert (2)
- Adam, Robert, 1728-1792.
- Alderman, Geo. P. B. (George P. B.) (4)
- Alexandria Hospital (Va.)
- Allegro, Jim
- Allen & Rocks (8)
- Allen & Rocks, Inc.
- Allied Architects of Washington, D.C. (6)
- Allied Bridge Designers of America
- Almond, A. Pearson (Alexander Pearson) (2)
- American Foreign Service Association
- American Oil Company (3)
- American Optical Company
- American Security and Trust Company
- American Society of Civil Engineers
- American Sociological Association (2)
- Ames, Anthony, 1944-
- Amoco Oil Company
- Anderson, Paul S. (4)
- Archetype (Firm)
- Architects Collaborative, Inc.
- Argyll, Marion H. (Marion Henry) (8)
- Ariss, John, approximately 1725-1799
- Arnold & Porter (8)
- Arnold, Fortas & Porter
- Arnold, Henry F.
- Art Metal Construction Co.
- Arthur Cotton Moore/Associates (2)
- Asher, Clyde B. (Clyde Blaine), 1883- (4)
- Ashford, Snowden, 1866-1927 (2)
- Associated Architects & Engineers (Washington, D.C.) (3)
- Associated Engineers (Silver Spring, Md.) (2)
- Atkinson & White, Architects (3)
- Atkinson, R. Bruce (Robert Bruce), 1883?-1952
- Austin, Laura A. Osborne
- Averill & Adams
