Stuff to visit while in Paris

1. Louvre, Orsay Museums and Centre Georges Pompidou -basically, all History from Mesopotamia to nowadays. They are the absolute must-see. You can count two days to visit the whole Louvre Museum (I’m not kidding, it’s HUGE. If you really want to appreciate, two days are great. One single day is too short unless you specifically choose not to visit periods you’re not curious about), 3 to 4 hours for the Orsay Museum and same for Centre Georges Pompidou.
2. Eiffel Tower. I wouldn’t recommend to actually visit it, just go there. The only fact to see it is breathtaking. It’s so huge that you feel like a little poor thing right under, it’s a nice thing to experience XD However, it’s pretty useless to actually visit it, because the only thing you get to see is Paris from the highest point. But, If I were you, I’d visit Montmartre for that, ‘cause seeing Paris’ roofs is much more impressive when you get to see the Eiffel Tower lost in the jungle of grey and red roofs :) 
3. Père Lachaise cemetary. Unusual but it’s just… wonderful! It’s by far my favorite place in Paris. But be aware, wear good shoes ‘cause you’re gonna walk, climb and jump a lot xD It takes a good day too to do the all cemetary.
4. Montmartre, very pittoresque. It’s the most touristic place in Paris but it’s still a must see. Breathtaking when it’s sunny. It takes an afternoon to visit. Bonus for the incredible view of the roofs as I said previously. 
5. Saint-Germain, to do some shopping and eat in great restaurants. It’s very chic. You’re gonna probably fall in love with Paris after visiting this area. I’d visit it by night, it’s even more charming in the darkness. About a day/ two nights to visit. 
6. Versailles. It’s out of Paris (30 minutes by train) but it would be a terrible mistake to come in France and not to visit the Royal Castle. It’s a huge domain, with the castle of course, and two little castles Marie-Antoinette used as a personal living space. The castle itself is gorgeous but I personally dig the two other castles (Petit and Grand Trianons) which are much more intimate and breathtaking (But it’s only my opinion). The gardens are also gorgeous but they’re only opened during summer. A day to do the three castles, two days if you add the gardens.
7. Cathédrale Notre-Dame de Paris. A must see as well, approximately 2 hours if you take your time.
8. Mouffetard street, if you’re into partying but like chilling with friends while drinking good stuff. 
9. Champs Elysées Avenue, if you’re more into clubbing. Also, you better get there early and very well dressed if you want to enter a club. A must-see by day too, it’s the so-called most beautiful avenue in the world so that’d be a shame to miss it xD Also, this avenue hurts your bank account right in the nuts, so you better lock your credit card in a vault or something considering the HUGE amount of incredible shops there :p. Useful information: all shops are open until midnight or so…
10. Bateaux-Mouches. I’d finish by that. It’s a 1 hour long beautiful ballad on the Seine river. You get to see every important building from the river and it’s a great conclusion for a trip in Paris. It’d make you remember everything you saw and it’s a great feeling. It’s the best postcard you can have. You can do it twice though, once by day and once by night, that can be fun ;)