There has always been an Underworld in Western literature (see Hades). As late as Dante's The Divine Comedy (written circa 1307-1321), it remained possible to put into serious imaginative form the traditional Christian notion that Hell lies below the surface of the world, just as Heaven is above. But understanding of the fact that the Earth is a globe became widespread, so that a writer like Giacomo Casanova (1725-1798), in Icosaméron (1788), allegorized the notion to depict an Eden-like interior world without much attempt at verisimilitude. Meanwhile, exponents of Scholarly Fantasy transformed the old flat-Earth concept into a vision of the surface of the globe as simply the outermost of a series of nested spheres, at the heart of which a small central sun shone.
So described, the HE may not be a plausible notion, but it was certainly arguable, and most tales set within our globe provide some form of explanation for the hollows within. HE stories are, therefore, almost invariably sf, like Journey to the Centre of the Earth (1863) by Jules Verne (1828-1905), though an author like Edgar Rice Burroughs, in his Pellucidar sequence, might well place tales there that have as little to do with the justification of scientific argument as any of his Planetary Romances set in the skies. The Hollow Earth (1990) by Rudy Rucker (1946- ) is a Recursive Fantasy set largely in the HE and featuring Edgar Allan Poe.