Warkworth Castle is a ruined, although reasonably well preserved castle, situated in Warkworth, Northumberland, on a defensive mound in a loop of the River Coquet. Warkworth Castle was originally constructed as a wooden fortress, some time after the Norman Conquest. It was later ceded to the Percy family, who held it, and resided there on and off until the 16th century. During this period the castle was rebuilt with sandstone curtain walls and greatly reinforced. The imposing keep, overlooking the village of Warkworth was added during the 15th century. It was refurbished, with much refaced stonework, by the Dukes of Northumberland in the late 19th century. The castle formed the backdrop for several scenes in Shakespeare's Henry IV, Part 1.

Alnwick Castle is a castle and stately home in Alnwick, Northumberland, England and the residence of the Duke of Northumberland. Built immediately following the Norman conquest, it was renovated and remodelled a number of times. The castle is used as a stand in for the exterior and interior of Hogwarts in the Harry Potter films. It has previously been a location used in Becket, Blackadder I, Robin Hood Prince of Thieves and many others.

Yves de Vescy, Baron of Alnwick, erected the first parts of the castle in 1096. It was built to defend England's northern border against the Scottish invasions and border reivers. The first Percy Lord of Alnwick restored the castle and the Abbot's Tower, the Middle Gateway and the Constable's Tower survive from this period. The 6th Earl of Northumberland carried out renovations in the 16th century. In the second half of the 18th century Robert Adam carried out many alterations. However, in the 19th century, Algernon, 4th Duke of Northumberland, replaced much of this with less ostentatious architecture designed by Anthony Salvin. A large amount of Adam's work survives, but little or none of it remains in the principal rooms shown to the public.

Ruthin Castle (the "Red Fort"), dates from before 1277 and dominates the historic Welsh market town of Ruthin. The castle sits in its ancient walled dry moat within acres of private landscaped gardens, parkland and woods alongside the River Clwyd. Ruthin Castle is built on a red sandstone ridge 100 feet above the Clwyd valley, overlooking a strategic river crossing. A wooden fort appears to have existed on the site until 1277 when Edward I reconstructed it in local stone and granted it to Dafydd, brother of Prince Llewelyn ap Graffudd. It was known as Castell Coch yn yr Gwernfor - the red castle in the great marsh. In 1282 the castle was under the control of Reginald de Grey, reputedly the former Sheriff of Nottingham who had just raised 'the finest army in the land' and defeated 'Robin Hood' and his followers. In 1646, during the Civil War, Ruthin Castle was destroyed by order of Parliament. In 1826 the modern castle was constructed and extended around, amongst and over the remaining ancient ruins, which are some of the oldest in Wales. Part of the ruins were incorporated in a large castellated mansion which took the name of the castle. Today the mansion is a luxury hotel, and all the old castle ruins are in the hotel grounds.

Warwick Castle (pronounced war-ick), overlooking the River Avon, lies in the town of Warwick of the English county of Warwickshire. Technically not a castle but a rampart, the history of Warwick Castle began in the 10th century. Legend has it that the first fortification of significance on the grounds of Warwick Castle was erected by Ethelfleda, the daughter of Alfred the Great, in the year 914. The remains of this ancient fortification can still be seen on Ethelfleda's Mound, a mound of earth at the southern end of the castle's courtyard. As intriguing as this legend is, the majority of the remains date from the period of Norman rule. In the year 1264, the castle was built by the forces of Simon de Montfort, who consequently imprisoned the Earl of Warwick at that time until a ransom was paid. Warwick Castle subsequently passed through seven generations of the Beauchamp family, who over the next 180 years were responsible for the majority of the additions made to Warwick Castle.