Is there a 3D space where the ratio of a circles circumference, C, to its radius, R, is C/R = 4*pi ? In two dimensions I can imagine a 2D surface that I think would work. In cylindrical coordinates let a surface be defined by z(r,theta) = A*r*sin(n*theta) For given integer n we can set A so the ratio of C/R is anything from 2*pi to infinity? If we travel on the surface z(r,theta) once around the origin at constant distance R the distance traveled will be greater then or equal to 2*pi*R? Can we just specify a space by giving the metric of some space? Let us say say that on some surface, ds^2 = dr^2 + [2*r*d(theta)]^2, this gives C/R =4*pi? Can we do something similar in 3D? ds^2 = dr^2 + [2*r*d(theta)]^2 + [2*r*sin(theta)d(phi)]^2 Does the above define some space such that C/R =4*pi? Thanks for any help!