In Paris you have so many things to see and places to visit that it is essential that you organize your trip so that you know where you are going to go and, above all, the attractions that you will visit. The best thing you can do if you want to visit Paris is to buy the Paris Pass , a card with which you can access more than 60 places such as museums , historical buildings, cruises, monuments, tours , etc. There are three different types, to choose from depending on the days you are going to be in the city and what you want to do. You can see all the detailed attractions here.
It is like a credit card and when you use it for the first time it is activated and from then on it tells you how much time it has. In addition, you will not only be able to access the attractions but you will be able to travel, among others, by metro and bus for free during the validity period that you have purchased, as well as being able to take a cruise on the Seine . The price of the Paris Pass for adults is € 89 for 2 days, € 124 for 4 days and € 149 for 6 days. There are special discounts for young people under 30 and for those under 18. It compensates, a lot.
When you buy the Paris Pass they will give you the Travelcard , which is the one you will use to travel on public transport and which is also activated when you use it for the first time. For your information, the Paris Metro is open from 5:20 to 1:20, almost 24 hours a day. To buy the Paris Pass, you can do it through their website and have it sent to your home or pick it up at a point of sale when you arrive in Paris. The surcharge for sending it to your home is quite high, so what I recommend is that you buy it directly there when you arrive since it is something that never runs out.