Before his appointment as Architect of the Capitol, J. George Stewart had been a professional engineer, the president of a general construction firm, and a member of the United States House of Representatives.

He is best remembered as the Architect who extended the east central front of the Capitol. Other projects carried out by Stewart included completion of the New (Dirksen) Senate Office Building and connecting subway system, the continued improvement and expansion of the Capitol Power Plant, the construction of the Rayburn House Office Building and its connecting subway system, and the House underground garages. In addition, preliminary plans for the James Madison Memorial Building of the Library of Congress were drawn under Stewart's direction.