What is the best way to get to Basilica Saint Denis from CDG airport?
According to the Journey Planner on the RATP (Paris Transportation) site, the simplest route would be to take the RER B from CDG to La Plaine-Stade de France and bus 253 from there to Basilique de Saint-Denis.
I really enjoyed going to the Basilica. We went from the 5th in Paris. It was a long ride but worth the trip. It was a very short walk from where we got off the subway or RER, whichever we used or used both. We had lunch in a resturant across the plaza or square from the Basilica. Enjoy!