Cha Cha's got it right. Why go all the way to Vatican City to see St Peter's when there's a replica right here? I've been to St Peter's and let me tell you - if you squint your eyes and lean your head to the left a bit, you'll swear you're right there...or not.
But still, its a pretty darn good try at making St Peter's in a smaller form and is a lovely addition to Montreal. Love the green roof and the nice little square it sits in which is lovely for sitting, sipping a coffee, and taking in the surroundings!