For those interested in history -- especially military history -- this is a treat. This historic base was established by Lt. Gov. John Graves Simcoe in 1793 to defend "little muddy York," as Toronto was then known. Americans sacked it in April 1813, but the British rebuilt that same summer. Fort York was used by the military until 1880 and was pressed back into service during both world wars.
You can tour the soldiers' and officers' quarters; clamber over the ramparts; and in summer, view demonstrations of drills, music, and cooking. If you can, try to visit on Victoria Day, Canada Day, or Simcoe Day, when there are plenty of special events. These include the ever-popular Kids' Drill, in which kids get to take part in a military exercise.