Berkhamsted Castle, is a ruined Norman Motte and Bailey castle at Berkhamsted in Hertfordshire. The castle is said to be unique in having a double moat.
The original fortification dates from Saxon times. Work on the Norman structure was started in 1066 by William the Conqueror who later passed the castle to his half-brother, Robert, Count of Mortain. In the 12th Century, the castle was home to Thomas Becket, Chancellor of England and later Archbishop of Canterbury. In the 14th Century, it became the residence of Edward, the Black Prince, and Geoffrey Chaucer was appointed Clerk to the Works. The castle has been owned by the Duchy of Cornwall since 1337.