The remains of the Castle can be visited
Tenby Castle

Tenby Castle, a historic fortification, stands on a headland connected by a narrow isthmus to the town of Tenby in Pembrokeshire, Wales.
History+
The origins of Tenby Castle date back to 1153, when it was first mentioned. It was founded by the Normans during their invasion of West Wales in the 12th century. As early as 1153, the castle was captured and destroyed by Maredudd ap Gruffydd and Rhys ap Gruffydd. In 1187, the Welsh besieged the site again. Although Llywelyn ap Gruffudd plundered the town in 1260, the castle remained intact. In the late 13th century, the castle became the property of William de Valence, who initiated the construction of town walls, which diminished the castle's defensive role. By the end of the 14th century, Tenby Castle had lost its military significance and fell into disrepair. In 1457, with the support of Jasper Tudor, a refurbishment of the town's defenses was carried out. During the Second English Civil War in 1648, the castle was held by Royalists for ten weeks before they surrendered to Parliamentarian forces.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:Part_of_Tenby_Castle_-_geograph.org.uk_-_893440.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 51.6723, -4.6955