Versailles is outside Paris (south-west). From Quai Voltaire you have a direct RER, line C : station "
Musee d'Orsay", RER C5 takes you to "Versailles Rive Gauche" it's the closest station from the Château de Versailles. It takes 30 to 45 mn from Paris to Versailles by RER. Yellow line C5 on the map : http://www.aparisguide.com/maps/rer.htm Versailles is N°18 on this map : http://...