It is unlikely. It is always best to talk to your Insurance Professional about the specific terms and conditions of your particular policy of course. The policy does cover “other structures” on your property such as sheds, fences etc. retaining wall by it’s nature is build into the earth, however so the greatest potentai hazard that might cause damage to it is earth movement which is excluded in your policy. This is much the same situation with a patio or your driveway as each of those are also build directly into the earth. Now, that having been said, should any of these be damaged as a result of a negligent act of someone else, like a contractor whom you may have on your property working for you, there may be coverage under their commercial liability policy.