Strongholds and fortresses are as old as history itself. They are a reflection of man's desire to be secure from his enemies. Most often they were constructed as military defenses—to keep enemies on the outside and families safe within. They were often built with massive walls of stone, defended with canons and armament.  In the 5th century B.C., the Chinese built the 4,000 mile long Great Wall to keep out invaders. But eventually it was breached. Ancient Smyrna constructed what many thought was an impregnable wall. It wasn't. Eventually it was compromised.