“The oldest parts of the walls were built in the seventeenth century,” continued our animated guidebook, “and the fort on the corner is Santiago. The big dome is the Cathedral and all the red tile roofs are convents and monasteries. The twentieth century hasn’t reached here yet. To all intents and purposes the Walled City is still in the Middle Ages.” The truth is that only part of the walls are really very old⁠—some parts have been built within seventy years.