I suppose it was inevitable that Patrick Blanc would be offered a spot at Chaumont-sur-Loire. He is easily the best known designer working with plants to create works of art in France. I've seen his work before, at the Parc floral de Paris and whilst I love the idea of creating a wall of tropical lushness, the reality seems to fall rather short once the wall has been up a year or two.
Not everything thrives in this vertical and artificial environment and the gardeners who maintain it don't necessarily understand what is required or have the resources to achieve it. Or maybe I just happen to see les murs végétaux too early in the year. This one must certainly have suffered in the cold winter we had.
It's called 'Spirale végétale' and it's in the courtyard of the stables in the Chateau Parc. The official blurb is here (in French).
PS My vote on this one is 'garden'.