RDH Architects Inc. | 1,496 followers on LinkedIn. A Toronto-based studio specializing in architecture for the public realm. | RDH Architects Inc. (RDHA) is a Toronto-based studio specializing in architecture for the public realm, and is the 2018 Royal Architectural Institute of Canada Firm Award recipient. Founded in 1919, RDHA is one of Canada’s oldest architectural practices, with a wide-ranging body of work encompassing library, industrial, office, recreation, post-secondary education, transit, and secure facility design.