Considered an 'eyesore' to many Parisians, the Montparnasse Tower has more than a few redeeming qualities. First off, it's miles less crowded than the Eiffel Tower itself. That's not to say it never has a queue, but if you choose off peak times you'll have no problem getting straight to the top of the tower for it's second, and best redeeming quality, the VIEW!
Because Montparnasse is the highest building in the city of Paris, it offers a truly unique vantage point of the Eiffel Tower and the surrounding city. The top floor is an open air 360 degree terrace complete with a restaurant and champagne bar. I haven't heard the best reviews about the restaurant but their's always the champagne. You know I never turn down a glass!
If you visit on a particularly cold or dreary day like I did (bummer!) you can get amazing views a few floors down in the enclosed 56th floor which has viewing binoculars.
How to get there : Montparnasse is a little bit out from your typical tourist spots, but well worth the extra 5-10 minutes to get there. There are several Metro trains that will take you to the large Montparnasse-Bienvenüe station, just be warned...this station is HUGE. I had to walk at least 5-10 minutes underground to reach the correct exit which is well signed once you're in the tunnels.
Bonus tip : If you're unlucky enough to visit on a foggy day the admission prices drop from €15 to €8 and the ticket agents can call to the top of the Tower to give you a visibility report before you ascend.
3 - Under the Eiffel Tower