Prince of WaLes Fort, Churchill (Manitoba)

It started as a log fort in 1717 on the west bank of the Churchill river by the Hudson´s Bay Company to protect and control the fur trade.
File:Churchill Fort Prince of Wales 1996-08-12.jpg
The structure still standing started in 1731 and had 42 cannons mounted on the walls. 
In 1782, three french ships led by frenchman Jean François de La Pérouse conquered it without firing a single shot!

John Mantha: Canadian Illustrator