May be its a bit distance from the center of Paris, but it worth a visit. I always wished to visit Montmartre in my fast trips to Paris and at the end I could do it. The best views of Paris are here,from the church of "Sacre Coeur" and if you go up the dome even better, really it worth it. But a walk around the streets is paramount to enjoy another Paris, the bohemian Paris, the ancient Paris, the ancient mills, the ancient establishments, meanwhile the big city is under our feet. Definitely is a unforgettable visit and an incredible sunset, if visiting late in the afternoon.
Montmatre district seen from the top of the Galeries Lafayette (Paris).