Continuously occupied by the Berkeley family since the 12th century, Berkeley Castle consists of a Norman, sandstone Keep with three semi-cylindrical turrets, and an Inner Ward surrounded by low-lying, 14ft (4.2m) thick walls. At one time there was a moat and the traditional Outer Ward to provide a defence strategy to the Inner Ward. The huge, round Keep is over 60ft (18.2m) high, and is one of the oldest parts of the surviving castle.

Robert Fitzharding was in occupation during the mid-12th century when he was given permission by Henry II to construct a castle made of stone, to replace the former timber construction. It was from the descendants of Robert Fitzharding, who liked to describe themselves as "of Berkeley", that lead to the family name still used today.

Berkeley Castle is probably most famous for the gruesome murder in 1327 of Edward II, who met his demise on the orders of the Queen and her lover. Edward's dungeon still remains virtually untouched. However, shortly afterwards the castle was rebuilt within its original walls, transforming the bare, Norman fortress into a splendid stately home. Therefore, much of what survives today dates from this later 14th century rebuilding programme. The Great Hall, with its saddle-beam timber roof and 'Berkeley Arches', The Long Drawing Room, The Small Drawing Room, The Dining Room, and a chapel with a timber roof, painted with texts translated from the Book of Revelations. Most of the furniture seen around the castle was brought over from France by the Eighth Earl at the beginning of the 20th century.

Berkeley Castle has been subject to little threat over the years, apart from during the Civil War when it suffered some superficial damage, which has meant that its structural appearance has remained much the same as when it was originally built. Today Berkeley castle, although still inhabited by the current generation of Berkeleys, is a thriving tourist attraction, with visitors not only coming to learn about the historical intrigue of this wonderful building, but also to enjoy the beautiful gardens and park surrounding it.