If you want the view of Paris, go up the Tour Montparnasse 18€ link

Paris is magical all year long from day into night. The Montparnasse Tower Observation Deck is open 365 days a year, 7 days a week, from 9:30 am to 10:30 pm Sunday to Thursday and 9:30 am to 11 pm Friday to Saturday without interruption, so you can admire the city whenever you want. The last lift to the top leaves 30 minutes before closing.