Arthur’s Seat in Edinburgh is the main peak of a group of hills formed from an extinct volcano that was active around 350 million years ago. It is the highest point in Holyrook Park, reaching an elevation of approximately 251 meters (823 feet) above sea level.
The origins of the name Arthur’s Seat is uncertain. The name “Arthur” could be a derivation of the Scottish Gaelic word Àrd-na-Said, meaning “Height of Arrows.”
One Arthurian legend says that Arthur watched his army defeat the Picts and Scots from the hill.
In a particular version of a legend, Arthur is not dead but in a state of eternal sleep, and it is said that he will one day return to lead his people again. The concept of a “sleeping hero” or a “king in the mountain” is prevalent motif in European folklore, and Arthur’s Seat is one of the locations associated with this legend in the British Isles.
See also
Cave Legend | The Legend of King Arthur
Source
Physical topography in Britain and elsewhere.