Gare RER de Saint Germain-en-Laye was created in 1847.
From Gare du Nord to Saint-Lazare, the only direct liaison is the RER underground train, line E. Follow the signs for "RER E - Haussmann - Saint-Lazare'.
The RER is a Paris suburban train service. It does not go to Le Havre. You can go from CdG to Gare du Nord on the RER, from Gare du Nord to Gare Saint-Lazare on the metro, and from Saint-Lazare to Le Havre by train. The SNCF website will help you with this.
RER line B towards Paris, until you reach the station "Gare du Nord" At Gare du Nord, switch to RER line E towards "Haussmann Saint Lazare" (next station)
Take RER B and get out at Gare du Nord stationChange for RER E and get out at Gare Saint-LazarestationTake metro line 3, heading towards Pont de Levallois and get out at Wagram station
From Roissy you take the RER Ligne B (Direction Saint-Rémy-lès-Chevreuse) to Châtelet-les-Halles and change onto the RER Ligne A (Direction Marne-la-Vallée) to Paris-Gare de Lyon.
RER E from MAGENTA
You take the RER ligne B (Direction Saint-Rémy-lès-Chevreuse) to Saint Michel, change onto the RER ligne C (Direction Versailles) and get off at Champ de Mars (at the rear end of the train).
Use the RER.
you take the RER
Simplest way is a No.26 bus, which leaves from directly outside the station, to the left as you exit from the main line area. Alternatively, you can go by RER - the express underground. Follow signs to the new MAGENTA station, approached through a pedestrian tunnel from Gare du Nord, which connects with Saint-Lazare.
There are 25 trains a day from Gare Saint-Lazare, or one can take the RER to Cergy-Pontoise, after which there is a regular bus service on to Gisors.
From le Havre, book a train to Paris. You will arrive in Gare Saint-Lazare. Get in the RER line E (you are at the end of the line, step in any train) Step down at the next station: "Gare du Nord" and take the RER line B3 (the direction is "Aéroport ROISSY Charles de Gaulle". There are two stations at the end of the line: CDG1-3 for the terminals 1 and 3, CDG2 for the terminal 2.