You can find churches and cathedrals in this WHS, but, if you can, you have to stay in Conques or Rocamadour overnight, both places will make you feel like you were a medieval pilgrim. St-Jean-pied-de-port is also a charming town, last stop before crossing the Pyrenees.

I've also been to: St-Sernin (Toulouse), St-Guilhem-le-Désert, St-Bertrand-de-Comminges, L'Hôpital-St-Blaise, Périgueux, Bayonne, Bordeaux, La Sauve, St-Gilles, the superbe Arles, Cahors, St-Lizier, Valcabrère, Figeac, Gavarnie (worth a day at the cirque), Rabastens, Amiens, Poitiers, Melle, Saintes, and the stunning Mt-St-Michel.