Building a wall of natural stone is hard work, and stone can be expensive. But the results are enduring and strikingly beautiful. Dry-laid stone walls rely on gravity, rather than mortar, to hold them together. As a result, they are more difficult to build than mortared walls because you spend more time getting stones to fit well and rest solidly on each other. Don't try to build a dry stone wall more than 3 feet high; it is difficult to keep it stable.