Plan to take this Rue Cler to Versailles trip in two steps:
I think I need a Metro ticket (zone 1) for 1st leg and then an RER ticket from Invalides. Is this correct?
Jim,
The easiest solution is to stop at the ticket window at Ecole Militaire and ask for return tickets to Versailles. The agent will provide the appropriate tickets. I made that trip last July and that's the method I used.
When boarding the RER, be sure to look for the word "VICK" in the window above the driver's compartment. Have a look at http://parisbytrain.com/paris-rer-c-schedule/ for more information.
Ken is correct. The Metro and RER tickets are interchangeable, but Versailles is out of the normal Zone 1 area for central Paris. More than one person has just taken the RER all the way to Versailles on a regular ticket and then been fined trying to exit. So if you buy your Versailles ticket at Ecole Militaire, they'll give you what you need. And buy the round trip so you don't have to stand in line again coming home.
Many thanks Ken and Douglas.
NEW PLAN: purchase a "Origine-Destination" RER ticket to Versailles Rive Gauche (train called VICK). Use this (only) ticket to get from Ecole Militaire to Invalides and then (same ticket) take the RER VICK train to Versailles Rive Gauche. If I buy a round trip ticket I can avoid possible delays to buy the return ticket.
Problem solved!
Bon voyage!
