Toronto, Ontario, Canada used to claim that Yonge Street was the longest road in the world, but that's because it hooked up with Provincial Highway 11 to run up to Lake Ontario and around to the Minnesota border. Even that linkage is now gone, so Yonge Street is definitely NOT the longest road in the world, no matter what anyone from Toronto might tell you.
The generally accepted longest road in the world is the Pan-American Highway, which starts in Alaska, and runs all the way down to the southern tip of South America. However, most of this is broken up into connected roads and highways that sometimes are not part of any 'official' Pan-American network. If you're going to use that as criteria, I think almost any road in North America could hook into that highway system at some point. Also, it's mostly rural highway, no shops or houses on most of it.
The Stroget in Copenhagen, Denmark is billed as the world's largest pedestrian street, lined with shops and cafes, but it's really more of a shopping district, comprising five or so nearby streets.