The Loire Valley is liberally doted with Chateaux which were built between the 15th to 18th centuries by kings and nobles. These stately homes and their vast gardens are open to tourists at cost.
Some of the highlights of the region include the medieval town of Blois which has steep, twisting medieval streets, the outstanding Chateau de Blois, and the Cathedrale Saint Lois.
Tours is a more cosmopolitan town as much of it was destroyed during WWII however there are some good museums and chateaux in the area and it's probably where most people will arrive in the area.
Amboise is a picturesque town not far from here with the Chateau d'Amboise on a rocky outcrop overlooking the town with great views of the valley. Leonardo da Vinci lived in Amboise for the last three years of his life and his house is open for inspection.