The large-scale geometry of hyperbolic metric spaces exhibits many distinctive features, such as the stability of quasi-geodesics (the Morse Lemma), the visibility property, and the homeomorphism between visual boundaries induced by a quasi-isometry. We prove a number of closely analogous results for spaces of rank n ≥ 2 in an asymptotic sense, under some weak assumptions reminiscent of nonpositive curvature. For this purpose we replace quasi-geodesic lines with quasi-minimizing (locally finite) n-cycles of r n volume growth; prime examples include n-cycles associated with n-quasiflats. Solving an asymptotic Plateau problem and producing unique tangent cones at infinity for such cycles, we show in particular that every quasi-isometry between two proper CAT(0) spaces of asymptotic rank n extends to a class of (n − 1)-cycles in the Tits boundaries.(CI n ) (Coning inequalities) There is a constant c such that any two pointsx, x ′ in X can be joined by a curve of length ≤ c d(x, x ′ ), and for k = 1, . . . , n, every k-cycle R in some r-ball bounds a (k + 1)-chain S with massHere, for a general proper metric space X, we use metric integral currents (see Section 2). However, if X is bi-Lipschitz homeomorphic to a finite-dimensional simplicial complex with standard metrics on the simplices, then (by a variant of the Federer-Fleming deformation theorem [36]) one may equivalently take simplicial chains or singular Lipschitz chains (with integer coefficients). (AR n ) (Asymptotic rank ≤ n) No asymptotic cone of X contains an isometric copy of an (n + 1)-dimensional normed space. Equivalently, asrk(X) ≤ n, where asrk(X) is defined as the supremal k for which there exist a sequence r i → ∞ and subsets Y i ⊂ X such that the rescaled sets (Y i , r −1 i d) converge in the Gromov-Hausdorff topology to the unit ball in some k-dimensional normed space (see Section 4)., the required inequality holds for the geodesic cone S from the center of the r-ball over R (see Section 2.7). Furthermore, any n-connected simplicial complex as above with a properly discontinuous and cocompact simplicial action of a combable group satisfies (CI n ); see Section 10.2 in [32]. Every combable group, in particular every automatic group, admits such an action.When X is a cocompact CAT(0) or Busemann space, the asymptotic rank asrk(X) equals the maximal dimension of an isometrically embedded Euclidean or normed space, respectively [52]. More generally, for spaces satisfying (CI n ), condition (AR n ) is equivalent to a sub-Euclidean isoperimetric inequality for n-cycles [81]; this result, restated in Theorem 4.4, plays a key role in this paper. If X is a geodesic Gromov hyperbolic space, then every asymptotic cone of X is an R-tree, thus asrk(X) ≤ 1. Conversely, a space satisfying (CI 1 ) and (AR 1 ) is Gromov hyperbolic (compare Corollary 1.3 in [81] and the special case n = 1 of Theorem 1.1 below).We remark that the asymptotic rank is a quasi-isometry invariant for metric spaces [81], whereas condition (CI n ) is preserved, for instance, by quasiisome...