Public Transportation in Versailles operates under the auspices of Keolis, the private operator of a large part of the country’s various other metropolitan transit systems. 

Phebus is Versailles’s subsidiary transport company, servicing the city and those eleven or so communities just outside its limits through the use of over 100 buses that traverse 24 routes and encompass pretty much all areas within Versailles.  The Phebus service shuttles over 50,000 residents and tourists every day.  This bus system connects to the SNCF trains that operate throughout the country and come and in and out of Paris.

You may find yourself taking a Phoebus Tourism Bus if you visit between mid-April and the end of October.  The Tour bus hits the interesting and vibrant quartiers (neighborhoods) of Saint-Louis and Notre-Dame before reaching le Palace Versailles, the city’s raison d’etre. 

Though public transportation in Versailles is more than satisfactory, if you are making a day trip from Paris to the Chateau, odds are you will never even hop a bus, seeing as how the palace is blocks away from the departure train stations.