Chenconceaux
Chateau de Chenonceau (Chenonceaux) - This magnificent chateau has a long and dramatic entrance, flanked on either side by formal gardens. Henri II gave the chateau to Diane de Poitiers in 1547. Diane laid out a marvelous Italian garden (the garden on the left as you're walking up), but when Henri II died, the Queen, Catherine de' Medici took over and made her own garden (the garden on the right).
After you've toured the chateau, there's a waxworks museum, maze to explore and woods along the river.
You can also hire boats and go boating on the Cher River.
In the evening, there is a Sound and Light show.
Castle Keep (Montrichard) - Just up the river, Montrichard has wonderful crumbly 11th century donjon, a several-storied stone castle that overlooks the city. Run up and down the ruins - there's a great view from the top. In summer, there are re-enactments of historic battles. Don't miss the Musee Ethnique, with waxwork figures in medieval costumes.
Along the Cher river, relax in the leisure park (parc de loisirs) where you can go pedal boating and play miniature golf. Or, rent canoes or kayaks to paddle on the river. In July and August, there are excursion boat rides also.
La Magnanerie (Bourre) - Visit a three story cave house and underground silk worm farm. On the tour, which lasts about an hour, you'll see the living areas and how people lived there in past centuries (this is a family-run tour, and the family still lives in the cave), plus demonstrations of quarry and silk work. Tours in French and English at 3:00, 4:00 and 5:00pm (plus 11:00am at high season), open April to November, closed on Tuesday (and Wed. in the fall).