It certainly fits the description of more than a house and less than a city, though it may resemble a house from the outside and a city from within. A point which became amply clear to me when I started to ponder whether they could have a small grove inside it, to grow woodland herbs. They have the valley, of course, where they raise their horses and let them graze, but they might have a stand of trees there.
Or I could just have them dependent on the lands they defend for their source. It's not like they aren't dependent on them for food. (And the prudent, practical fellow that he was, the wizard who erected this edifice ensured that they would get the food.)
And having given them a number of entrances, there is the question of how to keep them all defended at once. . . . which is thrilling because I just threw in the additional entrance to get around a plot point to make a particular scene. . . throwing stuff into the soup can inspire creative solutions in part because it can create quite tangled problems. . . .