In fact, men have always built some kind of fortification to protect themselves, their families, and their tribes against danger, whether from animals or from other men. In prehistoric times, as scientists can tell from ruins they have discovered, men used hills or ledges, and piles of earth and stone to make fortified places to defend themselves against their enemies.
Usually they did not live in such places, but only gathered there when danger threatened.
These earlier castles were made of earth and timber surrounded by a ditch.
From the 11th to the 12th centuries the Motte and Bailey castle began to appear and soon became very popular.
Castles also supported a large population without outside help and served as a center for social activity and local government.
Today, castles serve largely as places of interest for tourists.
Until gunpowder came about, there wasn't much that could bring a castle to the ground where it would most likely lay for the rest of its days.
Now, castles are considered to be largely tourist related places of interest.
A castle's fortification was the key to its military strength and protection.
Using two independent systems of walls made a breach almost impossible.