The birthplace of King Arthur. There is almost no place more legendary than Tintagel Castle. Technically there is no proof that Arthur ever existed, for sure. But the legends reach so far back in time and it's been a part of our collective memory and lore for so long, that hardly matters.
We have that loquacious Geoffrey of Monmouth to thank again for placing Arthur's birth here. It is here at Tintagel that Uther was ensorcelled by Merlin to appear as Igraine's husband Gorlois. He came to her and bed her, making Arthur and promising his get to Merlin for the deed. This particular part of the legend is very popular and makes its appearance in most subsequent legends after.