The Domaine de Fraisse is easily accessible by rail from all parts of France and Europe. The TGV station at Carcassonne is close by and transfers can be arranged for 6€ per person.
From Paris
Carcassonne can be reached in just over 5 hours on TGV from the Gare de Lyon in Paris with a change at Montpellier.
There is also a direct night service from Paris Austerlitz.
From Lyon
Direct TGV services from Lyon take around 3 hours and 15 minutes.
From UK
Through tickets with Eurostar can be purchased, changing in Paris.
Routes change constantly, for up to date information see www.tgv.com