Did MacNab actually call it that though? If not, when did people start the nickname?
"Dundurn Castle was constructed over a three-year period, and completed by 1835. Designed by a young English Architect, Robert Wetherall, Dundurn was built around the brick shell of Colonel Richard Beasley's colonial home. Designed as a fashionable Regency style villa, Dundurn (Gaelic for "strong fort") was nicknamed "Castle" by the citizens of Hamilton. The Castle, with its gardens, grounds and many unusual outbuildings, was one of the finest estates in the province."
http://www.hamilton.ca/CultureandRec...urn_Castle.htm
What's funny is someone updated the
Wikipedia page based on the April Fool's joke.