During this period, he earned awards from Anglin Norcross and Hobbs Glass and designed several theatres and concert halls.
As the final work during his studies, Dimakopoulos designed the foundations of the Queen Elizabeth Auditorium in Vancouver, British Columbia, in 1954.
In 1955, he participated in the creation of the Affleck, Desbarats, Dimakopoulos, Lebensold, Michaud & Sise architecture firm, which changed names in 1970 to become ARCOP (Architects in Co-Partnership).
This firm worked with Henry N. Cobb and Ieoh Ming Pei on the design of Place Ville-Marie, a landmark skyscraper in Downtown Montreal.
The firm later worked on other major projects in Quebec and the rest of Canada, including Expo 67, Place Bonaventure in Montreal, and the National Arts Centre in Ottawa, Ontario.