Magical spaces similar to demiplanes in real-world myths and folklore?

[Clistenes]

{{Scrubbed}}

[SpanielBear]

Similar to Tuatha de Danan, to the point of being pretty much an Arthurian/high Middle Ages expy is the Isle of Avalon, the realm of the Lady of the Lake that Arthur is taken to and from whence he shall return, etc.

Fiddler’s Green is another such space, a more modern Anglo myth I believe but a place stumbled across by chance that is peaceful and restful.

[Clistenes]

{{Scrubbed}}

[LibraryOgre]

The Mod Ogre: Discussion of real-world religions, even when couched as "mythology", are against the rules of this forum.