Name: Niels Klim’s Underground Travels by Ludvig Holberg
Author: Ludvig Holberg

This first edition was issued with a fold-out engraved map depicting the subterranean world of Niels Klim. Centred on the radiant inner sun, it shows the planets and lands of Holberg’s cosmos, including the realm of Potu and other fantastical territories encountered in the tale. By offering a cartographic image of an imaginary world, the map reinforces the work’s conceit of travel literature while giving tangible form to Halley’s theory.

Ex Carta

Holberg’s Nicolai Klimii Iter Subterraneum features a fold‑out map of the subterranean world, centred on an inner sun and its orbiting lands. The chart visualises a hollow‑earth cosmos, lending a pseudoscientific imprimatur to its satire and fantasy.

The first edition, in Latin, of the novel by Ludvig Holberg (1684–1754) later translated into English as 

. It is a pioneering work of imaginative fiction written by a leading figure of Danish–Norwegian letters, with ‘a superbly inventive and entertaining narrative’.

The book quickly established itself as a classic of subterranean fantasy and exercised a formative influence on later writers, most notably Jules Verne. Although Holberg’s conceit resembles Edmond Halley’s cosmological theory that planets are composed of concentric spheres surrounding a central sun, it is questionable whether Holborg was directly influenced by Edmund Halley’s work.

As ‘almost certainly the first portrayal of a hollow Earth’, it is also the antecedent to an entire genre of imaginative fiction in which the protagonists encounter a fantastical subterranean realm: Jules Verne’s 

 novels (1914–1963) of Edgar Rice Burroughs, 

 (c.1929) by H. P. Lovecraft, and the bizarre series of accounts written by Richard Shaver (1907–1975), and published in Amazing Stories magazine in the 1940s, in which he claimed to have encountered malevolent entities living in cavern cities deep within the earth.

, set in 1665, relates how the student Niels Klim falls into a cavern near Bergen and discovers a hollow world within the Earth. At its centre burns a miniature sun around which orbit inhabited planets. Klim lands on Nazar, in the kingdom of Potu (‘utopia’ reversed), where he encounters communities of intelligent tree-like beings, before voyaging through a series of marvellous societies. Holberg’s tale, both satirical and fantastic, combines Swiftian parody with Enlightenment rational enquiry, its humour sharpened by social critique.

Holberg is regarded as the father of modern Danish–Norwegian literature. Norway and Denmark were politically integrated at the time and Holberg was born in Norway though educated and resident in Denmark for most of his life. His oeuvre spanned comedy, history, philosophy, and fiction, with Niels Klim his most widely translated and enduring prose work. His blend of satire, moral reflection, and imaginative invention places him firmly within the European Enlightenment while also anticipating the speculative fiction of the nineteenth century.

Title page and portrait of Niels Klim

Fold‑out map of the Subterranean World

An engraved portrait of a Potuan Citizen, or 'tree-man' from the utopian society of Potu

An engraved portrait of a Citizen of Martinia wearing a wig

This first edition was issued with a fold-out engraved map depicting the subterranean world of Niels Klim. Centred on the radiant inner sun, it shows the planets and lands of Holberg’s cosmos, including the realm of Potu and other fantastical territories encountered in the tale. By offering a cartographic image of an imaginary world, the map reinforces the work’s conceit of travel literature while giving tangible form to Edmund Halley’s theory.