If it isn't on your calendar already, get out a red pen and mark November 26. That's National Cake Day, and although we don't need any excuses to enjoy the star of any birthday, wedding, or Tuesday afternoon, it got us thinking: where is the best travel destination for a day dedicated to celebrating cake?Our conclusion: Austria, with not one, but two flagship cakes.Linzer TorteLinz is the home of Linzer Torte. Since it's said to be the world's oldest cake recipe,...