The Tour Montparnasse has great views of the Eiffel Tower (without the ugly tour montparnasse in it! ), the Père Lachaise cemetery is very cool. Wandering the streets around the sacré coeur basilica (and the church itself! ), the Sainte-chapelle stained glass is gorgeous! The musée d'Orsay is my favourite museum of all time- I didn't really like the Louvre! You can also climb the arc de triomphe which is quite cool!