It’s not unusual for homeowners to spend thousands of dollars erecting a retaining wall.  Most quality homeowner insurance policies are worded consistently on this issue.  A retaining wall is considered a Detached Structure and the maximum amount of coverage is usually 10% of your Dwelling Coverage limit.  The retaining wall is usually covered for damage caused by Fire, Lightning, Wind (including tornado), damage caused by vehicles and a few other types of perils.  HOWEVER, most of the damage that I have seen arises from retaining walls falling due to saturated soil.  This usually happens when we have experienced an extremely wet period lasting 3 or more days.  This falls under the Earth Movement policy exclusions and is not covered.