Darmstadt, Germany: Wissenschaftliche Buchgesellschaft, 1959. Hardcover. First Edition. First Wissenschaftliche Buchgesellschaft Edition, reprinting Riemann's 24,  Index pp. 12mo. Light terracotta cloth coverd boards with gold titling to spine. Clean, crisp copy with previous owner's signature in ink on first free endpaper. Text in German. Fine.
Translates to "On The Hypothesis Which Underlies Geometry" and originally delivered by Riemann in 1854. Riemann's work on "Riemann Geometry" was later used by Albert Einstein in the development of his theories.