Love them (as a sci-fi geek) or loathe them (as a claustrophobe), France's 24-hour self-cleaning toilets are here to stay. These mechanical WCs are free. There is no time for dawdling either: you have precisely 15 minutes before being (ooh la la!) exposed to passers-by. Green means libre (vacant) and red means occupé (occupied).
The French are completely blasé about unisex toilets, so save your blushes when tiptoeing past the urinals to reach the ladies' loo.