Basically a maple-leaf-emblazoned version of the Gap, Roots designs athletic, plaid-accented streetwear that's unmistakably Canadian. Its retro-style jogging pants, hoodies and toques (if you don't know what that is, this is the place to find out) are ever-popular. There are additional outlets (usually in malls) throughout the city.
Check the sale rails for end-of-season deals. You might even pick up an ironic trappers hat for just a few bucks. If you're Australian, you'll know the name of this store has naughty connotations back home; which means it's a good place to buy a T-shirt souvenir emblazoned with the Roots legend.