The Metro is the best way to get around the city, but since it's underground you miss out on the scenery. You may want to take the bus to see more of the city. It uses the same tickets as the Metro, so it's simple to switch between the two. Electronic placards at the front of each bus display the current location and upcoming stops, and each stop is well marked. It's a convenient and intuitive system.
Noctambuses run several routes at night between 01:00 and 05:30 from Monday night to Saturday night. They're an excellent choice for getting around late at night, though they have a separate ticket and charge for more than one transfer.
For travel within central Paris and its immediate surroundings, a Mobilis day pass can come in handy. Three-day, five-day and weekly passes are also available. The bus is especially attractive for places outside the city like Versailles and Disneyland. You can get a chance to see parts of France that you otherwise wouldn't taking the Metro.
RATP (Regie Autonome des Transport Perisiens)
Telephone: +44 0892 68 41 14/77 14