It's not that an $11 bowl of official San Francisco clam chowder doesn't hit the spot. And, granted, there's no substitute for an authentic Machu Picchu souvenir visor. But not all overcrowded ...

In other words, sorry, but giving yourself a stamp at Machu Picchu simply doesn't count. "The Department of State advises U.S. citizens to avoid the use of novelty stamps in the U.S. passport.

If you’re a frequent traveler, then you may one day run into an offer for a souvenir passport stamp. Antarctica offers a stamp at some of its scientific stations, Machu Picchu offers a stamp at ...