Alien : Early Ridleygram with entrance of the egg silo exterior references HR Giger's "National Park"

 

 

leading from

Alien: The Egg silo
and
Ridleygrams
and

Prometheus: Pyramid in The Prequel
and
HR Giger's "National Park"

Ridley's sketch of head on Egg Silo

A skull from Giger's painting National Park from 1975.

clearer version of the image

Giger's painting "National Park " from 1975.