You can avail of train, bus, or taxi to transfer from Charles de Gaulle airport(CDG) to the city center of Paris. Taxi is a better option with a fixed charge to Paris city. Go to the taxi pickup zone from arrival terminals. While going to the airport, it is best to catch a taxi from Gare du Nord or Gare de l'Est because overall fare will generally be cheaper from these points. Uber is also available. Roissybus or Air France Bus is useful when you are traveling areas near the Arc de Triomphe, the Opera area, Montparnasse Tower, or Gare de Lyon.