"The Parisians have been building historic attractions for more than 1500 years as part of a coordinated effort to kill any visitors to their city who manages to escape French drivers.
The key is *stairs*. Most tourist attractions, such as L'Arc de Triomphe (the Lark of Triumph) and the Hunchback of Notre Dame Cathedral, have some kind of lookout point at the top that you - the tourist - are encouraged to climb via a dark and scary medieval stone staircase containing 5789 steps and the skeletons of previous tourists. (You can tell which skeletons are American, because they're wearing sneakers.)
If you make it to the top, you are rewarded with a sweeping panoramic view of dark spots before your eyes caused by lack of oxygen.
Meanwhile, down on the street, the Parisians are smoking cigarettes and remarking, in French, "Some of them are still alive! We must build more medieval steps!"
So...please...wear your most comfortable shoes (something not too ugly!) and you'll be prepared to see Paris on many different levels much more enjoyably...using stairs, of course!

