Gréber is best known for the 1917 master plan for the Benjamin Franklin Parkway in Philadelphia; for his work as master architect for the 1937 Paris International Exposition; and for the Greber Plan for Ottawa and the surrounding National Capital Region. The latter, produced between 1937 and 1950 (with an interruption during the Second World War), included expansion of urban parks, a series of parkways, and a greenbelt surrounding the city. The plan incorporated the construction of a national cenotaph and surrounding plaza area.