This hop-on, hop-off bus tour runs open-deck buses along four circuits (central Paris; Montmartre–Grands Boulevards; Bastille–Bercy; and Montparnasse–St-Germain) daily year-round. You can jump on and off at main sites, making them very convenient for whirlwind tours of the city. Cityrama, which owns the buses, has a host of other packages as well.