The familiar continuum R of real numbers is obtained by a well-known procedure which, starting with the set of natural numbers N = ω , produces in a canonical fashion the field of rationals Q and, then, the field R as the completion of Q under Cauchy sequences (or, equivalently, using Dedekind cuts). In this article, we replace ω by any infinite suitably closed ordinal κ in the above construction and, using the natural (Hessenberg) ordinal operations, we obtain the corresponding field κ-R, which we call the field of the κ-reals. Subsequently, we study the properties of the various fields κ-R and develop their general theory, mainly from the set-theoretic perspective. For example, we investigate their connection with standard themes such as forcing and descriptive set theory.2010 Mathematics Subject Classification 12L15, 12J15, 12L99 (primary); 03E10, 03E15 (secondary)