Based on Ben Nicholson's reconstruction of a set of hidden pavements within the Laurentian Library, the authors have hypothesized a system of geometry which may have led to many of the ancient masterpieces of architecture and design. The constituent parts of an ancient geometry, consisting of five major components are presented. Based on these principal geometries, a hypothetical taxonomy of ancient sacred geometry is presented. A proposal is made showing how this taxonomy relates to the pavements of the Laurentian Library.