The Dream-Quest of Unknown Kadath
Lovecraft's own "The Nameless City" (1921), which also deals with the exploration of an ancient underground city that is apparently abandoned by its nonhuman builders, sets a precedent for "At the Mountains of Madness". In both stories, the explorers use the nonhumans' artwork to deduce the history of their species. Lovecraft had also used that device in "The Dream-Quest of Unknown Kadath" (1927)