that the world above ground does not exist. The Third Eye (1956) by Tuesday Lobsang Rampa mentions contact with advanced beings living in the center of the Earth. The End of the Tunnel (aka The Cave of Cornelius) (1959), by Paul Capon. Four boys in England get trapped in a cave by a landslide, and by following the cave, they encounter a forgotten civilization. Dark Universe (1961) by Daniel F. Galouye. A post-apocalyptic science fiction novel where two clans live deep underground and are descendants from humans who escaped an old war. City of the First Time (1975) by G.J. Barrett. British survivors of an atomic holocaust venture downward into the earth through a series of caves and encounter two other races, survivals of previous extinctions. Visages Immobiles (1983) by Raymond Abellio. Having discovered that New York was built on top of a massive hollow cavity, an architect devises a plan to build an underground city below Manhattan. The underground setting then becomes the scenario of the apocalyptic battle between a clairvoyant and an international terrorist. A Hollow Earth featured in the children's Choose Your Own Adventure novel The Underground Kingdom (1983). The history of the Hollow Earth theory is explored in Umberto Eco's 1988 novel Foucault's Pendulum, alongside a wide range of other pseudo-scientific and conspiracy theories. Rudy Rucker's novel The Hollow Earth (1990) features Edgar Allan Poe and his ideas. Rucker claims in an afterword to have transcribed the novel from a manuscript in the University of Virginia library; the call number given is that of a copy of Symzonia. The Dark Elf Trilogy (1990–1991) by R. A. Salvatore was the first of the Forgotten Realms books to describe the underground world of the Dark Elves called the Underdark. This greatly helped popularize underground settings in fantasy RPGs. The novel Indiana Jones and the Hollow Earth by Max McCoy (1997) expands on the legend of an advanced civilization in the Earth's interior. Reliquary (1997) by Douglas Preston and Lincoln Child features an underground civilization of humans beneath Manhattan. The short story "Black as the Pit, From Pole to Pole" by Howard Waldrop and Steven Utley continues the journey of Frankenstein's creature through a hollow Earth. In Jeff Long's 1999 novel The Descent and its 2007 sequel Deeper, a vast labyrinth of tunnels and passages underlying the Earth is inhabited by a brutal species of once-civilized but now degenerate