  Let G be a discrete group which acts properly and isometrically on a complete
CAT(0)-space X. Consider an integer d with d=1 or d greater or equal to 3 such
that the topological dimension of X is bounded by d. We show the existence of a
G-CW-model E_fin(G) for the classifying space for proper G-actions with
dim(E_fin(G)) less or equal to d. Provided that the action is also cocompact,
we prove the existence of a G-CW-model E_vcyc(G) for the classifying space of
the family of virtually cyclic subgroups such that dim(E_vcyc(G)) is less or
equal to d+1.
