You can't say you've been to Paris until you've seen the Eiffel Tower. The tower named after the engineer who designed and built it is one of Paris' most famous attractions to date.
Several people visit this monument over the course of the day and the lines to climb to the top seem never-ending. While most take the elevator to the top-most viewing platform, the stairs which seem to be a very tiring route is rather interesting. The slow climb from the bottom more than makes up for the amazing views. The tower when lit up at night makes quite a fascinating picture when compared to the view of the tower in the day.