In 1854, in Gottingen, Riemann gave the famous lecture «On hypotheses underlying geometry», where he gave an extended concept of space. Penetrating into the depth of Riemann’s thought and developing it, the author logically states the following: Riemannian manifolds in the broad sense, in the concept that Riemann himself attached, are innumerable and exist in the real world. It remains to comprehend and accept the fact of their existence in the real world.