With all the slopes in the Hill Country retaining walls are a must. Retaining walls can increase the usable surface of your surface of your propriety by tierring or terracing. Retaining walls can be constructed with natural materials such as boulders or chopped stone. They can be constructed with the dry stack method or mortared depending on the height and load bearing weight. Most retaining walls are constructed with masonry joints for strength. Proper drainage is also important.