There are six major train stations in Paris, each of which handles traffic to different parts of France and the rest of Europe. The most spectacular route is via the Channel Tunnel ; the Eurostar passenger service takes only three hours. TGV (train à grande vitesse) services also link Paris with Amsterdam and Brussels. France's superb domestic rail network can take you to almost every part of the country.
With the Eurotunnel service, you can now drive from London to Paris, with your car neatly on the shuttle train. If driving from elsewhere in Europe, once you're in France modern autoroutes will get you to Paris quickly, if rather expensively.
Paris is surprisingly pedestrian-friendly: it's compact and there are few hills. Watch out on pedestrian crossings, though - cars tend not to stop.
There are river shuttles along the Seine, but these cater more to tourists wanting to slowly soak up the sights along the way than to commuters trying to get somewhere.
Parisians don't much like to share the road, and cycling in this city is no joy. To make matters worse, bikes aren't allowed on the metro.
In case you hadn't guessed it, driving around Paris is a job best reserved for the terminally aggressive - if you don't have lots of time to kill, you're better off taking public transport, which is generally well-maintained and supremely convenient.
Say what you will about driving around Paris, but the city's public transportation is world class. The most charming of Paris' public transport options, the underground Métropolitain (and its sister system, the RER), is a simply massive network. No matter where you are, chances are there's a metro station within a few blocks. Choose travel passes carefully - depending on how many trips you make, daily passes aren't necessarily good value for money. The weekly (also monthly) Carte Orange travel pass can be a better deal, even if you're staying less than a week.
The public bus system covers everywhere, but its hours are laughable; don't even try it on Sunday or a holiday. The Noctambus network takes over in the heavily trafficked areas once both the underground and the day buses go to sleep.