That track is what was formerly known as Mosport. Probably the most famous track in Canada. Canadian Tire bought it a while back, and have actually put a fair amount of money into it since then.

They have a "big track" and a smaller driver development track. I've run autocrosses on the DDT a few times, and also done one of the open wheel courses there - both highly recommended. If you're passing by you can usually park and wander in, even if the gates are closed. I usually stop if I'm in the neighbourhood.