here and when SM Stirling's Sir Nigel Loring looks up at Mount Angel:
"...in this light it seemed otherworldly... the pale whitewash shining as if carved from a single opal and lit by some internal glow."
-SM Stirling, A Meeting At Corvallis (New York, 2007), Chapter Fifteen, p. 379.
When it rained:
"...the fortress-monastery vanished like a castle in a dream." (p. 380)
Poul Anderson could write about Ivar Frederiksen sailing a ghost ship across a dead sea and SM Stirling could write about Sir Nigel entering a castle in the Otherworld but they don't happen to be writing that kind of fiction right now.
Fantasy and sf connect in the characters' minds. In Anderson's "The Saturn Game," astronauts exploring a very hard sf environment, an outer moon, lose themselves in a fantasy role play with dramaric results - but the fantasy does not become literally true. This is not that kind of fiction.