Notre Dame Cathedral

What luck: a second monument in Paris that adults and kids both recognize! The Eiffel Tower, of course, is the best-known; but -- thanks to Victor Hugo's book Hunchback of Notre Dame, not to mention Disney's version-- most kids will be familiar with this great cathedral, too. 

Above is the view of the "Cathedrale de Notre-Dame" on the side that overlooks the Seine. The "rose window" is renowned, and Notre Dame (pronounced not-ra-dam) itself is probably the most famous Gothic cathedral in the world. On the right half of the building, you can see the famous "flying buttresses."