The cut polytope of a graph is the convex hull of the indicator vectors of all cuts in and is closely related to the MAXCUT problem. We give the facet-description of cut polytopes of -minor-free graphs and introduce an algorithm solving MAXCUT on those graphs, which only requires the running time of planar MAXCUT. Moreover, starting a systematic geometric study of cut polytopes, we classify graphs admitting a simple or simplicial cut polytope.