A fortification was built at Oxwich, near the south edge of the Gower Peninsula, in the 13th century or earlier, but the building that stands on the site today dates from the 16th century, constructed in two phases by members of the Mansell family. Although referred to as a castle, perhaps partly because of the previous structure, the place is instead a fortified mansion, or manor house, centred on a rectangular courtyard which is lined by rooms on two sides, up to six stories tall. The large scale and the defensive elements of the house were designed to impress visitors rather than repel attacks, as by the time of its construction south Wales was a peaceful place, free from the campaigns and rebellions of previous centuries.
The south range of Oxwich Castle, the first to be built, was in more recent times used as a farmhouse, and this survives intact, now housing a museum, while the larger, more elaborate and slightly later east range has been ruined since the 18th century, though constitutes the most interesting and photogenic part of the site.
The castle has a rather isolated location along the north edge of a promontory of land between Oxwich Bay and Port-Eynon Bay, about 220 feet above sea level, and the upper floors were high enough to overlook several miles of the coast. The north side adjoins a strip of woodland, which hides the castle from the village below, at the foot of a steep slope, while the south side faces farmland.
In medieval times Oxwich was owned by the Penrice family, occupiers of nearby Penrice Castle; both places passed to the Mansell family in 1410, by marriage of Sir Hugh Mansell to the Penrice heiress. The oldest sections of the current building are the courtyard, the entrance/gateway and the south range, built between 1520 and 1538 by Sir Rhys Mansell (died 1559), who had become prosperous by courting the Tudor king Henry VII, while the elaborate east range was added in the 1560s and 1570s by his son Edward Mansell (died 1595). The house was fully occupied for only around 50 years, in part due to the large expense in maintaining such a complex dwelling, and by the 18th century only the smaller, more manageable south range was still in use, by tenant farmers, the Mansells having long since moved to a new dwelling on the site of Margam Abbey. The mansion was acquired by the government in 1949.
The approach to the castle is along a narrow lane, climbing from Oxwich village, then a short distance east on a lesser track to a parking area, in front of the castle. The site is managed by Cadw and the exterior can be viewed at any time, though access to the interior is only possible between April and October, Wednesday to Sunday. One separate feature is the ruin of a 16th century dovecote, on the lawn below the west wall of the manor; all other buildings are arranged around the courtyard. The northwest side is lined by a low wall, originally somewhat higher, and along the southwest side is the grand, military-style gateway, incorporating the carved stone coat-of-arms of the Mansell family. A higher wall section links the gateway to the two storey south range, which has whitewashed walls, in contrast to the austere, grey masonry of the remainder. The ground floor of the south range (originally a kitchen) houses the entrance station, Cadw gift shop and museum, while above is a full-length room containing period furniture, clothing and other artefacts, accessed from staircases at each end. The southern stair is contained within a D-shaped turret that helped guard the gateway; there may once have been a similar tower on the far side.
The East Range
The most spectacular part of Oxwich Castle is the east range, along the northeast side of the courtyard. The south walls survive approximately to their full height, though the north side walls are mostly missing right down to ground level, with the exception of the square tower at the southeast corner, which is still the original six stories tall, just lacking its roof and all floors. The main section of the range consisted of three cellars overlain by the two-storey great hall, illuminated by two multi-light windows, next to various service areas including the steward's day room, steward's bed chamber, nursery, pantry, buttery and dresser, then above was the long gallery, spanning the full length of the building, giving spectacular views over the peninsula from its large windows. The east side of the hall linked to bed chambers, on two levels, which in turn connected to the tower that provided more accommodation space, for the family and their visitors. A similar tower at the opposite side of the east range has mostly disappeared, as has a less tall tower at the center. The east range was entered from the courtyard through a porch, which collapsed in the 18th century; several windows and doors on the frontage show where later modifications have occurred.