Computational Algebra methods have been used successfully in various problems in many fields of Mathematics. Computational Algebra encompasses a set of powerful algorithms for studying ideals in polynomial rings and solving systems of nonlinear polynomial equations efficiently. The theory of Grobner bases is a cornerstone of Computational Algebra, since it provides us with a constructive way of computing a kind of a particular basis of an ideal which enjoys some important properties. In this paper we introduce the concept of Hadamard ideals in order to establish a new approach to the construction of Hadamard matrices with circulant core. Hadamard ideals reveal the rich interplay between Hadamard matrices with circulant core and ideals in multivariate polynomial rings. Our approach yields an exhaustive list of Hadamard matrices with circulant core for any specific dimension.