I haven't found any really good tutorial on this, but I would like to add some underground content. In my particular case, it's not a rail station. However, even if it was, I'm wondering how to do it. I've tried lowering the ground around a smallish office/hotel building (the building is actually placed off to the side while this is done) and adding concrete slabs and then placing the object I wish to place (a swimming pool). The thing is, the "underground" really isn't that big - it would be the size of a short, small, maybe one or two-track station if I were trying to place trackage. Perhaps put another way, the underground area would be 100x50 or 50x50 feet. Ideally, it would be nice to create a rectangle in the ground, about 12 feet down, place some concrete slab for flooring and some pillars are supports, and place my building over top. Isn't there an easier way to manipulate earth or is it really this difficult?