In 1069, William the Conqueror dispatched Robert Cumin and a company of 700 soldiers to Durham with orders to secure the unruly northern borders of his new kingdom. They were massacred. In retaliation, the king devastated the region.
To stamp his authority and keep control over the area, William had basic fortifications overlooking the town hastily thrown up. He made this stronghold the base for his great bishops: a defence against the Scots, a warning to the rebellious.
As the prince bishops grew in power and wealth so their fortress residence grew in status until it became one of the most richly decorated palaces in the country.