Castle keeps come in many shapes - circles, squares, rectangles, and other polygons - and these choices were not accidental. In this post, I explore the geometry of castle keeps, how mathematical considerations influenced medieval military architecture, and what you can still see today when visiting historic sites and museums.
I'm no square
I recently took time out for a quick weekend away in South Wales. The itinerary involved, as is only right, castles[1]. I was struck by the geometric shapes of the keeps - particularly one with a circular cross-section at Tretower castle, and a larger one with a hexagonal base that forms part of Raglan castle.
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The Circular Keep at Tretower
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T. Briggs is
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