Unlike many of the other grand castles in south Wales, the large, extravagant and beautifully designed structure at Raglan does not date from the Norman period, though a basic motte and bailey fort may have existed at that time; instead, construction began in the mid 15th century, under a minor Welsh nobleman, William ap Thomas (later William Herbert). The place was continuously occupied until the English Civil War (1642 to 1646), after which, by order of the crown, it was deliberately damaged (slighted), in order to prevent any future role in military conflicts, and it has remained in a ruined state ever sense apart from some sections that were refurbished in the 1800s.
Despite the partial destruction, and subsequent removal of materials for other building projects, the main structures are essentially complete, and the castle presents very impressive spectacle; a jumbled amalgam of towers, walls, steps, stairways and arches, in a variety of architectural styles. The most prominent section, and one of the oldest, is the hexagonal great tower which is completely surrounded by a moat that is still full of water; a relatively rare occurrence, as the majority of castle moats are now dry.
Today, Raglan is one of the most popular Welsh castles, partly due to its large size and good preservation, but also on account of its easy access, close to the junction of the major roads A40 and A449. At least two hours could be spent exploring the various towers and corridors, and reading the many informative notices installed throughout the site.
Raglan Castle was built purely as a private residence, and was home first to the Herbert family and then (after 1492), having been transferred by marriage, to the Somerset family who were the Earls of Worcester and later Dukes of Beaufort, all direct male-line descendants of Edward III. Surviving components from the initial structure include the moat, the great tower and the gatehouse, all constructed of the local Redbrook sandstone, yellowish grey in colour; other parts of the first design have been replaced as the buildings were expanded, in the late 15th century, at various times in the 16th century and at the start of the 17th century. The later additions used the more widespread Old Red Sandstone, also mostly grey but with a red or purplish hue. At its peak, the fortified mansion was surrounded by landscaped gardens, fish ponds and terraces, and overlooked a lake, and the whole site was considered equal in grandeur to any other castle in the kingdom.
The Somerset family were Royalists, and during the Civil War the castle was besieged by government forces, surrendering in August 1645 after several months of resistance. The family recovered the partly ruined castle some years later, though it remained little used and unrepaired until the 1820s when some parts, including the great hall and the grand staircase were refurbished, and the castle was used for banquets. The castle came under government control in 1938, after being donated by the 10th Duke of Beaufort.
In contrast to other castles initially built for defensive purposes, Raglan is not sited at any particular geographical landmark like a hill or river crossing; instead it lies amidst rolling farmland, a mix of green fields and patches of woods, half a mile north of Raglan village. The A40 passes by to the south, just west of the junction with the A449, and access is along a short, narrow side road, leading to a grassy parking area beside the low wall at the front of the complex. Entrance to the castle is through the gift shop/visitor centre, along a path that leads to the main gatehouse. Close by, partly shielded by trees, is Castle Farm House, an elegant, red brick building dating from around 1630, originally the castle stables. Part is now used as a visitor cafe.
Although the entrance path leads to the impressive gatehouse, flanked by two smaller towers and one larger (the closet tower), the most eye-catching feature is the hexagonal great tower on the left, completely surrounded by a most filled with greenish water, partly covered by lily pads. The tower is entered at the first floor level by a wooden bridge (originally a French-style drawbridge) leading from the central courtyard. All interior floors are long gone, and a great gash in the exterior is a result of slighting after the Civil War, yet the tower retains most of its original height, and the top is still accessible, via a set of stairs, and this gives the best overall views of the site. The wide base of the tower, also hexagonal, is enclosed by lower apron walls and small corner towers, with space for visitors to walk all around, while the far side of the moat is also lined by a pathway.
The main section of the castle includes the grassy square of fountain court on the west side, lined on three sides by apartments, with the secondary entrance (the south gate) at one corner and the grand staircase at the other, above two cellars. To the east the court adjoins the chapel, and the long gallery above; these in turn border the great hall, dias and buttery. The eastern half of the castle is centred on the pitched stone court, another open area so named because of the pebbles used in the construction of the floor; this has the pantry at one side, the kitchen and larder in the northeast corner tower, offices down the far side and finally the gatehouse complex to the southeast. The castle has around 14 towers of which half to be climbed, at least in part. The views extend across many miles of farmland towards the Black Mountains in the west and the lower hills of Gloucestershire to the northeast.