When Andrew Carnegie established his institution for discovery in 1902, he left to the trustees and administrators the task of organizing and running it. In 1905, the trustees passed a resolution to construct a new building, a structure that would reflect the quality and excellence of the institution’s work and symbolize its permanence in the nation’s capital. They engaged John Carrére and Thomas Hastings, architects trained in the Beaux Arts style, to design a building “as nearly fire-proof as practicable,” and with ventilation good enough “so that life in it may be tolerable during a tropical summer.” Carrére and Hastings were among the most prominent architects of the time, indeed of the century. Their sophisticated legacy includes the landmark New York Public Library (1897), the Cosmos Club in Washington, D.C., and the Russell Senate and Cannon House Office Buildings on Capitol Hill.
Andrew Carnegie believed the institution should be known for the grandeur of its work, not the grandeur of its surroundings. In keeping with a limited budget, and to appease Mr. Carnegie's objections to a grand edifice, the drawings for the new building underwent several revisions, becoming less monumental with each one. Nonetheless, the architects managed to maintain a sense of elegance and proportion commensurate with the building's location on one of the grand thoroughfares of the city. The authors of Sixteenth Street Architecture, a book published by the U.S. Commission of Fine Arts, in 1988, place the building among the most distinguished on Sixteenth Street.
The building was constructed during 1908 and 1909 by the J.E. & A.L. Pennock Company of Philadelphia. Work was slowed by errors in the original survey, a strike among the ornamental plasterers, and an outbreak of typhoid among the limestone cutters in Indiana, yet the quality of construction remained high. The steel structure was encased in terra cotta for fire protection. Ventilation was achieved with large operable windows and skylights.
The building's solid, neoclassical facade is an impressive presence. Its monumental portico is surmounted by a flat-top roof and supported by Ionic columns. Huge marble urns, copies of originals in the Vatican Collection, flank the entrance steps. The massive bronze doors at the top lead inside to a two-story rotunda, framed by large Corinthian columns and an elliptical side staircase. Large offices with twelve-foot ceilings and elaborate cornices line the rotunda on both floors. Natural light plays across the rotunda floor, as well as the wide hallways and second-floor library, swept in from a sophisticated system of skylights not visible from the Sixteenth Street entrance. Also hidden from view is the building's ground floor and 1938 addition, which extends back along P Street.
The addition was conceived in the late 1920s, when the institution realized the administration building was too small to accommodate its growing public lecture and exhibit programs. Although, the Capital Science Lecture program was curtailed during World War II, it was reinstated in 1991. The trustees voted to add a new addition in 1930, but financial uncertainties delayed completion until 1938. The architects, Delano & Aldrich, designed a 400-seat auditorium, an exhibit hall, and a new entrance on P Street, blending the classical style of the original building with a distinctive modernist touch. Especially noteworthy is the way the architecture complements the painted surfaces of the auditorium's interior. Wrapping around the entire room is a unique set of murals by J. Monroe Hewlett. Hand-painted in a style reminiscent of N. C. Wyeth, the murals depict a group of heroic figures—astronomers, geographers, and explorers typifying the researchers of the institution. In the ceiling above, are lighted transparencies of the sun and moon.