History has a habit of making the Middle Ages look surprisingly tidy. The Romans disappear. Castles start to appear (everywhere). Knights arrive. Everyone starts speaking in suspiciously Shakespearean English. Lots of fighting. That's not what happened.

1066 was a rather big year for castles in England. Before this date there were four, maybe five, castles found in the whole country. By 1100, just thirty-four years later, there were over five hundred!