Abstract Let M be a manifold, and g a Riemannian metric on M . Then there is a unique, preferred connection ∇ on TM called the Levi-Civita connection, which is torsion-free and satisfies ∇g = ∇0. The curvature R(∇) of the Levi-Civita connection is called the Riemann curvature, and its holonomy group Hol(∇) the Riemannian holonomy group Hol(g) of g.