Paris Travel Guide - HTML5

the RER trains travel on to the Parisian suburbs, outside the zone where a regular subway ticket can be used.  Travel outside the city centre without a valid RER ticket will get you fined, and the packs of inspectors who roam the system show no mercy to tourists pleading ignorance. In particular, Charles de Gaulle airport is not within the city; you must purchase an RER ticket to get there (see Get in ). The Métro and RER move staggering numbers of people into, out of, and around Paris (6.75 million people per day on average), and most of the time in reasonable comfort. Certain lines, however, are operating at or near capacity, sometimes being so full that