[2] Pope traveled for two years through Italy and Greece, where he studied, sketched and made measured drawings of more Romanesque, Gothic, and Renaissance structures than he did of the remains of ancient buildings.

Pope designed private houses, such as The Waves, his personal residence in Newport, Rhode Island,[4] and public buildings in addition to the Jefferson Memorial, the National Gallery of Art, the Masonic House of the Temple, all in Washington, D.C., and the triumphal arch Theodore Roosevelt Memorial (1936) at the American Museum of Natural History in New York City.

He designed the extension of the Henry Clay Frick mansion in New York City that created the Garden Court and music room, among other features, as the house was expanded to be operated as a museum.

[citation needed] Lesser known projects by Pope's firm include Union Station, Richmond, Virginia (1917), with a central rotunda capped with a low saucer dome; it now houses the Science Museum of Virginia, the Branch House (1917–1919), a Tudor-style mansion in Richmond, now housing The Branch Museum of Architecture and Design; the Baltimore Museum of Art; and in Washington, D.C., the National City Christian Church, DAR Constitution Hall, American Pharmacists Association Building, Ward Homestead, and the National Archives Building (illustration, left).

Pope designed additions to the Tate Gallery and British Museum in London, an unusual honor for an American architect, and the War Memorial at Montfaucon-d'Argonne, France.

The Georgian Revival residence he built in 1919 for Thomas H. Frothingham in Far Hills, New Jersey has been adapted as the United States Golf Association Museum.

He also served on the Board of Architectural Consultants for the Federal Triangle complex in Washington, D.C.[7] During the 1920s, the firm designed a number of well known country estates including Spring Hill Farms, later renamed Cobble Court.