Polynomial multiple recurrence over rings of integers

We generalize the polynomial Szemer'{e}di theorem to intersective polynomials over the ring of integers of an algebraic number field, by which we mean polynomials having a common root modulo every ideal. This leads to the existence of new polynomial configurations in positive-density subsets of ${\mathbb{Z}}^m$ and strengthens and extends recent results of Bergelson, Leibman and Lesigne on polynomials over the integers.