Cornwall - Saint Michael's Mount
Type of spiritual experience
Of particular interest is Evans-Wentz's assertion that it was a site used for the Mysteries.
A description of the experience
The Fairy-Faith in Celtic Countries, by W.Y. Evans-Wentz, 
AT ST. MICHAEL'S MOUNT, MARAZION
Our next place for an investigation of the surviving Cornish Fairy-Faith is Marazion, the very ancient British town opposite the isle called St. Michael's Mount. ….. It is believed, … that Marazion was the chief mart for the tin trade of Celtic Britain, and that the Mount--sacred to the Sun and to the Pagan Mysteries long before Caesar crossed the Channel from Gaul--sheltered the brilliantly-coloured sailing-ships of the Phoenicians. In such a romantic town, where Oriental merchants and Celtic pilgrims probably once mingled together, one might expect some survival of olden beliefs and customs.