The northernmost place* I've been in the world is the Sognefjord in Norway. In North America, Edmonton, Alberta.
The southernmost place I've been in the world is Davis, California. In Europe, Provence, France.
The easternmost place I've been in the world is Serbia (either Belgrade or somewhere on the way to or from Čačak). In North America, Cape Spear, Newfoundland -- as far east as you can go!**
The westernmost place I've been in the world is Tofino, British Columbia. In Europe, London, England.
* on land; my recent flight from Frankfurt to Vancouver took me over Greenland and the high Canadian arctic.
** unless Greenland counts.