Visit the Chateau Gaillard in Eure, Upper Normandy
An extraordinary feat, Chateau Gaillard was built in just one year - 1196/7 - for English King Richard I (Richard the Lionheart). Richard died from a wound during the course of the construction. The location is ideal for defensive purposes, being raised on a rocky spur high above the River seine (and the village of Les Andelys).
The purpose of the castle at that time was to protect Normandy, then in the hands of the English, from the French.
The castle walls were built as a series of 19 round arcs, an innovative feature at the time, because of their greater ability at deflecting attacks, and the improved view out that they provided to the archers inside the castle.
However just a few years after its construction Gaillard castle was sieged and seized by the French, in an impressive display of strategy. This included building a covered walkway to reach the bottom of the tower, using the walkway to carry rubble with which to fill in that section of the moat, and then building a fire that undermined the tower. Ultimately a section of the tower collapsed allowing access to the outer part of the castle.
The next defences of the castle were breached via the chapel - or possibly the chapel toilet, depending who you believe. Access to this section enabled the French to lower the castle drawbridge, and ultimately for Philip II of France to seize it from the English.
In the early 14th century the castle was used as a prison, with prisoners including Margaret of Burgundy, the adulterous wife of Louis X - she was strangled with her own hair at the prison in August 1315.
In 1417, during the Hundred Years War, the castle fell back into English hands - after a siege of 16 months, the last remaining rope for raising water from the castle well finally wore through and the castle had no choice but to surrender. At the time of the construction the well had been hacked out through many metres of rock, in itself an extraordinary feat.
The castle changed hands twice more before finally returning conclusively to the French in 1429.
Gaillard castle remained in use until the 16th century, when it was ordered to be destroyed by Henry IV after yet another siege.
Map showing location of Chateau Gaillard