Completed Projects See pictures below of completed projects by Retain Terrain in rock, boulder and concrete sleeper walls: B Grade Sandstone Retaining wall with Sandstone Steps feature This Sandstone Boulder Wall is both a functional and stunning feature for this pool area. A Grade Sandstone Boulder Retaining Wall with Aluminium fence set into the stone. Random Sandstone Boulder Retaining wall to created useable space on a steep housing block. These Terrace Boulder Retaining Walls increase the useable space on a housing pad. This Boulder Wall was created on a housing pad with tight access. These Rock Walls increase the useable land on this house block as well as adding a stunning garden feature.