1. Eiffel Tower. Who doesn’t think Paris and not see the Eiffel Tower in their mind? It is actually the most visited paid monument in the world. Built in 1889 for a World’s Fair, this structure, still the tallest in the city, was named for the engineer who constructed it, Gustav Eiffel. There are restaurants on the first and second floors; you can buy tickets to ascend to these levels either by stairs if you are fit, or by elevator if you prefer. You must take an elevator to the highest, or third, level.