Loches, 42km southeast of Tours, is the obvious place to head for in the Indre valley. Its walled citadelle is by far the most impressive of the Loire valley fortresses, with its unbreached ramparts and the Renaissance houses below still partly enclosed by the outer wall of the medieval town.

The northern end of the citadelle is taken up by the Logis Royal, or Royal Lodgings, of Charles VII and his three successors. It has two distinct halves; the older section was built in the late fourteenth century as a kind of pleasure palace for the Dauphin Charles and Agnès Sorel. A copy of Charles’s portrait by Fouquet can be seen in the antechamber to the Grande Salle, where in June 1429 the Dauphin met Joan of Arc, who came here victorious from Orléans to give the defeatist Dauphin another pep talk about coronations.

From the Logis Royal, cobbled streets lined with handsome townhouses wind through to the far end of the elevated citadelle, to the donjon, the best preserved of its kind in Europe. You can climb up to the top of the massive keep, but the main interest lies in the dungeons and lesser towers. The Tour Ronde was built under Louis XI and served as a prison for his adviser, Cardinal Balue, who was kept locked up in a wooden cage in one of the upper rooms. Perhaps he was kept in the extraordinary graffiti chamber on the second floor, which is decorated with an enigmatic series of deeply carved, soldierlike figures that may date from the thirteenth century. From the courtyard, steps lead down into the bowels of the Martelet, which was home to a more famous prisoner: Ludovico “il Moro” Sforza, duke of Milan, patron of Leonardo da Vinci and captive of Louis XII. In the four years he was imprisoned here, from 1500, he found time to decorate his cave-like cell with ruddy wall paintings, still faintly visible. The dungeons peter out into quarried-out galleries which produced the stone for the keep.