Don't take a taxi in Paris. Take the metro.

The métro system is clearly the best way to get around Paris. It’s orderly, inexpensive and for the most part safe. You’re rarely far from a métro station in Paris. They are marked by a yellow “M” in a circle or by those incredibly beautiful Art Nouveau archways with “Métropolitain” on them. Although you may be confused when you first look at a métro map, simply follow the line that your stop is on and note the last stop (the last stop appears on all the signs) and you’ll soon be scurrying about underground like a Parisian. Service starts at 5:20am and ends at 1:20am (one additional hour on Saturday night/Sunday mornings and the eve of holidays). Métro tickets are also valid on buses. The cost of a métro ticket is €1.70. A carnet of 10 tickets costs €11.70, and the price of a Passe Navigo (a week pass from Monday through Sunday) is €22.50.