It also has affiliated offices in Vancouver, Los Angeles (Adamson Associates, Inc.), New York (AAI Architects, P.C.)
Gordon Sinclair Adamson (1904-1986) started the firm in 1934 after working for a number of other architects (F. Hilton Wilkes and Edwin Kay), as well as noted Henry Sproatt and Ernest Ross Rolph.
His practice was mainly residential, commercial, and industrial projects in Ontario.
The firm's main offices in Toronto are located at 401 Wellington Street West, formerly McGregor Socks factory.
[2] Adamson entered into the contest to design the new Toronto City Hall in 1958.