The nearest airport is Toulouse (Blagnac), which is serviced by Air France/KLM, British Airways and Easy Jet amongst others, and is a 50-minute drive from the château. Ryanair flies into Carcassonne airport which is also reasonably close (1hour 45 minute drive), and Bergerac, Bordeaux, Brives and Rodez airports are also possibilities (between 2 and 2½ hour drives).
TGV trains from Paris arrive into Agen and Toulouse, and there is an overnight train between Paris and Toulouse.
From all transport hubs it is necessary to hire vehicles to reach the Château as public transport is infrequent and only runs to nearby towns. Having your own vehicle is also necessary if you want to reach shops and other amenities.
Minibuses and taxis can be hired locally.