On the opportunity cost of castles.

Whether the castle could have survived much longer once gunpowder became prevalent is actually a moot point. Its very strength was a barrier to the growth of great national governments. Monarchs regarded private castles as an inherent threat. Legal and other measures were taken to eliminate them. In Britain, the Tudors were particularly effective in eliminating great noble castles as part of a well designed program to establish the state’s monopoly on violence. In France, Louis XIII probably destroyed more castles than he built. This trend was actually a paean to the military virtues of the castle.