Brobdingnag is a fictional land in Jonathan Swift's 1726 satirical novel "Gulliver's Travels" occupied by giants. Lemuel Gulliver visits the land after the ship on which he is travelling is blown off course and he is separated from a party exploring the unknown land. In the second preface to the book, the author laments that this is a misspelling introduced by the publisher and the land is actually called Brobdingrag.

The map printed at the beginning of Part II indicates that Brobdingnag is located on the northwest coast of North America between Japan and California. It shows (from south to north) Point Monterey, Port Sir Francis Drake, Cape Mendocino, Cape St Sebastian, Cape Blanco and the semi-mythical Strait of Anián, all locations depict Brobdingnag as a peninsula extending west into the Pacific to the north of the Straits. Swift describes the location of Brobdingnag, and its geography, in the text of Part II of "Gullivers Travels", and provides a map showing where it is.

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