Canberra, the capital city of Australia, was planned by Walter Burley Griffin, an American architect and planner. He won the competition in 1912 to design the city, and his plan was based on the idea of creating a garden city with a blend of nature and modern urban design. Canberra was officially founded in 1913, and its design incorporated a combination of natural elements and geometric planning.
Therefore, Walter Burley Griffin is the correct answer.