Retaining walls - are they really hard to build? No, they are not, provided you understand how gravity works, know what frost can do, understand erosion and rain and realize that humans judge things as being correct when they are level.
When I went to Michigan State University, one of the classes I took while getting my Horticulture degree was called Landscape Construction. One of the many things I learned in this valuable class was how to build proper retaining walls. One of the most common errors that I see when looking at other retaining walls, particularly boulder retaining walls is that the boulders are set incorrectly - upside down. All boulders were created with one flat side. This flat side occured when the volcano blasted the hot molten stone from its chimney and it landed and cooled on the Earth's surface millions of years ago. Many people set this flat side down when in fact the flat side should be up so that we all look at the wall and judge it to be level. Sure, its alot easier to put the flat side down, but that is the professional challenge.
Another mistake I regularly see is the absence of fabric behind the retaining wall. At Landscape Magic we always install a heavy geotextile fabric between the retaining wall material and the soil or backfill stone behind it. This fabric prevents soil erosion, yet allows water to escape under pressure through the crevices in the wall.
Under most circumstances we build our walls horizontally, left to right, one course at a time, backfilling, compacting and trying to select stones that will appear level as much as possible.
If you are interested in a retaining wall, call my cell phone direct and I will be happy to meet with you to discuss your options. 248-866-4887.