Cloisters, Norwich Cathedral

Canada actually has some 11th-century buildings, George -- Viking houses in Newfoundland and Labrador. The Vikings don't live there any more, though; they were all excavated in the 60s. Actual buildings that are still being used go back to the 17th century (in Quebec), so compared to Australia Canada is positively ancient.

West of the Great Lakes, though, is more like Australia, with the oldest buildings from the early to mid-19th centuries.