Closest town/city the rail system reaches:
Best way to find transportation"
Trains run from Toulouse to Foix, Tarascon sur Ariege, and Ax-les-Thermes, but you may need top pick up a car in Toulouse, instead.
My husband and I visited Montsegur and I believe you will need a car to get as close to the town and castle of Montsegur as possible. We don't take trains in France because my husband is willing to drive and we like to see many out of the way places by car.
If you rent a car, you can visit the small town of Montsegur. The town has a small museum about the Cathars. Your drive to the site of the castle doesn't take too long from the town. We did not climb to the top of the castle. We did climb a rather steep hill to look at the monument that is located on the trail.
Once you have a car, you can also visit many other Cathar sites. We found them to be very interesting and we did climb Peyrepertuse.
I hope you enjoy your trip!