Dundurn Castle in Hamilton, Ontario, is a National Historic Site built between 1834 and 1835 for prominent politician Sir Alan Napier MacNab. This 18,000-square-foot mansion represents exceptional architectural ambition for the young colony, combining Classical and Italianate design elements. The brick structure features distinctive French windows, broad verandas, three-storey square towers, slate roofs, and a prominent Doric portico added in 1855. Built at the remarkable cost of $175,000 and equipped with innovative conveniences like gas lighting and running water, the castle overlooks panoramic views of the adjacent bay. The surrounding estate integrates Gothic Revival outbuildings, 1812 military earthworks, and 18th-century farm buildings, now restored and open to visitors.