Born in Philadelphia, Nolen studied economics, philosophy, and public administration at the Wharton School of the University of Pennsylvania. Various jobs in parks and gardens complemented his early career as an educator. In 1903, at the age of 34 with a wife and children, Nolen returned to school to pursue landscape architecture as a profession. At Harvard he studied under Frederick Law Olmsted, Jr., and Arthur Shurcliff. He opened his office in Harvard Square in 1905. The firm completed over 450 projects, including comprehensive plans for 29 cities and 27 new towns in this country. Nolen also traveled frequently abroad to study foreign planning models. Typically his work provided multi-year consulting for municipalities. Strong administrative, economic and philosophic convictions provided an underpinning for his work. In his pioneering work in parkway design, he believed that circumferential highways and parkways benefited cities and merited tax support. As a leading city planner, he influenced a generation of professionals. Nolen played an important role in multiple professional planning organizations, including the National Conference on City Planning and the International Federation of Housing and Town Planning. His influence extended beyond his consulting through his publications including New Ideals in the Planning of Cities, Towns and Villages (1919) and New Towns for Old (1927).