The Castle can be visited
Tintagel Castle

Tintagel Castle is on a peninsula on the west coast of Cornwall in the United Kingdom. Its exposed location and connection to the Arthurian legend make it a place of historical and cultural significance.
History+
Although there are few traces of pre-Roman or Roman settlement, finds suggest a possible Roman trade route. Excavations in the 1930s initially pointed to an early Christian Celtic monastic complex between the 5th and 8th centuries. However, more recent research from 1990 to 1999, based on high-quality imported goods from the Mediterranean and Spain, suggests that Tintagel was a princely seat from the mid-5th to the early 7th century, maintaining Roman-ancient traditions. A slate find from 1998 with a Latin inscription confirms the continuation of late antique culture in Southern England.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Colin Jackson
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: 50.6672, -4.7585