I have a Las Vegas to Rome flight booked with Air Canada, which gives me an 11-hour layover in Montreal. My luggage will go directly through to Rome from Las Vegas, so I won't need to get it in Montreal.
I already have my eTA for transit through Canada. Can I leave the airport for a sightseeing tour of Montreal? Will it be okay with Customs & Immigration? I'll carry just a small carry-on backpack with me.