Yes I have it, I play quite often, at least 2-3 times a week for a couple hours straight. I have built many structures, from fortresses that are virtually impregnable, all the way to cliff fortresses, towers, and on our private server we even carved our own island out of land and built a huge fortress on it, on the outside there is water, then its our outer wall with 4 towers on each of the corners, the towers have tunnels dug below our walls leading to the middle of the compound. On the inside of our outer wall we have a lava moat, and then on the inside of our lava moat we have our secondary wall which is higher than the outer wall so we can overlook.