Most modern stuff is easier to scratch build or like Irongrave says, use Pike Stuff. The detail is simpler on modern structures, mostly smooth with some ribs. It wouldn't be worth casting, brick or stone you could do but not to large with plaster, it just don't work well. I cast a real long retaining wall in many sections that's as tall as a two story building but is glued against Styrofoam. A large structure standing alone will be problems.