Medieval castles, whether in ruins or restored, dominate the varied landscapes of Europe. Stone fortifications were nothing new to the continent, but during the Middle Ages, there was an explosion of castle construction as feudal lords sought to consolidate their power and provide fortresses for the inhabitants of their kingdoms. Some were described to be little more than dirty, cold stone boxes, but others evolved to become impressive reminders of years past.

Many people today cling to a romantic view of castles-complete with knights, damsels in distress and nonstop medieval feasting. Research shows that castles served a very utilitarian role in feudal society. It was protector, visible landmark, and source of pride among many communities.

Soon after the collapse of the Roman Empire, Germanic tribes began to construct heavy stone fortifications. Near the first millennium, another force would greatly spread the use of castles in Western Europe. William the Conqueror, from Normandy, France, invaded England in 1066 and changed the medieval landscape forever. Medieval societies soon witnessed the erection of stone towers and walls in every country. Simple Norman donjons evolved into more elaborate strongholds with towering walls, defensive systems and could house sometimes thousands of people.

The castle remained a prime military resource for much of the Middle Ages. Military tactics centered on the taking of castles, and weapon technology improved over the centuries to exploit any weakness that could be found in castle architecture. It wasn't until the late 1600s, when gunpowder and artillery became more effective, that the castle became obsolete. Many fell into ruins during the succeeding centuries, but there remain excellent examples of medieval castle architecture that have been beautifully restored.

From: http://www.medieval-castles.net