Since a fence is a relatively permanent structure, you will want to be sure of the location of your property lines before construction. A prudent course of action is to locate existing property corners that delineate your property line and have the validity of the monuments verified by a surveyor. If you are unable to find your property corners, ask for assistance from your surveyor. They may be able to find monuments using a magnetic locator and cloth tape. If the surveyor is not able to locate existing monuments, you may need to have a monumented land survey performed.