Well firstly, it will depend what you consider constitutes sacredness. For me, all land is sacred (just some bits bear more marks of human occupation than others), so the Pyrenees and the Black Mountains, the Med and the Atlantic are all holy places to make pilgrimage to.
If our human ancestors are sacred to you (as they are to me), then the many caves they occupied and left paintings in over thousands of years might be places you want to go- there are loads of such sites in SW France and Northern Spain.
Then there are the many strands of the Camino which run through SW France, leading pilgrims to the End of the Earth, a journey that was holy long before the Christians became custodians of the pilgrim infrastructure.
There are many Templar sites that I came across when I lived in Castres and explored the area - Les Tours for example, though they weren't really sacred for me.
Most cities are built on sites that for one reason or another were special to their first occupants - maybe for springs or rivers that flowed there, or high places, or important things that happened there, so Toulouse, Carcassonne, Albi (or any other city) might all be sacred to you. Often churches are built on top of older shrines.
If the arts are sacred to you, then maybe some of the amazing artwork in the region might be worth reverence, Tolouse-Lautrec, Gaudi, Picasso and Dali all have art on show in SW France and Catalonia (very close if you are anywhere near the Pyrenees). When I lived in France, I went to the Dali musiem in Giron for the day and saw a beautiful exhibition by an artist who assembled natural rocks to create goddess type figures which he then made portraits of on canvas - both stunning and memorablel.
The coast of Languedoc was occupied by Greeks, Phoenicians and Romans, so there is plenty of classical archeology to be explored and the Basque country has a non indo-european history of it's own. You could take a trip to the Virgin on the Rock near Biarritz. Many amazing places in southern Europe have been Christianized like this but retain their magic and mystical attraction none-the-less.