The Neanderthal lived throughout a widely divergent climate and habitat. These peoples adapted quickly to new environments as they migrated. Some lived in caves, while others built shelters out of branches and animal skins. Still others dug pits and covered them with branches, animal skins and leaves.
Ideas are like rabbits. You get a couple and learn how to handle them, and pretty soon you have a dozen.
Lewis & Clark stayed near present day Astoria, Oregon during the winter of 1805-06, and built Fort Clatsop for shelter.