It was built by architects Thomas W. Fuller and James H. Craig and originally served as Toronto's federal customs clearing house. It remains a federal property, currently housing a number of administrative and support functions for Canada Revenue Agency.
Halifax also has a building named "Dominion Public Building". It was built in 1929. (See List of old Canadian buildings.) Hamilton had a "Dominion Public Building" too, built in 1935-36, which is now the John Sopinka Courthouse.