Cro-magnon and Neanderthal shelter on the Dordogne river in southern France.  This shelter could have housed up to five thousand human beings.   Nearby is Lascaux cave.  Modern man used these shelters to escape religious persecution, first the Protestants then the Catholics.   Protestants used ladders to get into the shelters then pulled the ladders up as pursuing Spanish Catholics tried to engage them.  (See artist conception of Cro-magnon hominoid).
 

Early man lighting his shelter.   Also see Native American shelters.