The Keep on the Borderlands is a Dungeons & Dragons adventure module by Gary Gygax, first printed in December 1979. In it, player characters are based at a keep and investigate a nearby series of caves that are filled with a variety of monsters. It was designed to be used with the Dungeons & Dragons Basic Set, and was included in the 1979–1982 editions of the Basic Set. It was designed for people new to Dungeons & Dragons. The Keep on the Borderlands went out of print in the early 1980s, but has been reprinted twice; a sequel was also made. A novelized version of the adventure was published in 2001. The module received generally positive reviews, and was ranked the 7th greatest Dungeons & Dragons adventure of all time by Dungeon magazine in 2004. Plot summary Player characters begin by arriving at the keep which they can adopt as a base before investigating the series of caverns in the nearby hills that are teeming with monsters. These Caves of Chaos house multiple species of vicious humanoids. Plot twists include a treacherous priest within the keep, hungry lizardmen in a nearby swamp, and a mad hermit in the wilderness. It typifies the dungeon crawls associated with beginning D&D players, while permitting some limited outdoor adventures. When The Grand Duchy of Karameikos edition of the Gazetteer series was published, the Keep was given a specific location in the Known World of Mystara, in the Atlan Tepe Mountain region in northern Karameikos. Original publication The Keep on the Borderlands was published in 1980. It consists of a 32-page booklet with an outer folder; the module was written by Gary Gygax, with cover art by Jim Roslof and interior illustrations by Erol Otus. It is designed for use with the Dungeons & Dragons Basic Set. It was included in printings 6–11 (1979–1982) of the Basic Set, although it was also available for sale separately. The cover of the first printing included the notation, "With minor modifications, it is also suitable for use with ADVANCED DUNGEONS & DRAGONS"; this was removed from later printings. The module's cover notes that it is especially designed to help beginning players and Dungeon Masters (DMs). Tips for running encounters appear throughout the text to assist beginning DMs. The module also provides rudimentary rules for wilderness adventures, as these were not included in the D&D Basic Set. The structure