Gruen's early work was in the fields of individual store design and residential projects. He is regarded as a pioneer in modern store design in work ranging from small shops to large department stores. Gruen turned to shopping center design early as a challenging new field of architectural expression. He again won praise, As this firm expanded, the scope of his professional work grew to include such diverse projects as office buildings, private homes, public and tract housing projects, and the planning of complete communities including homes, apartment buildings, office buildings, shopping centers, civic buildings, schools, and recreational facilities. His unique achievements in these fields, especially in the design of shopping centers, have led him in recent years into the field of city planning and urban redevelopment