Château de Brézé is a very interesting chateau outside of Saumur. You don't visit it for the chateau above ground which includes a dry-moat, you visit it for its trogloditic basement where some of the chateau's vineyard activity takes place. It's also quite old, dating back to 1060.
Underneath you explore kitchens, an old bakery, the wine presses and silk worm farm area as well as secret passages. Save time to do some wine tasting in the cellars as well!