Recently purchased a home, and in the very back yard is an old concrete block shed-like structure. We're not sure when it was built, but would like to put it to use. After getting boundary survey, appears about 3 ft of structure is over the property line (using the corner iron pins to establish the line). Recent deeds of both ours and our neighbors, however, describe the boundary line as "recommended to be established as a "line of agreement"". When looking at this "line of agreement" (established using the angles/distances in the deeds), the line is moved just enough so that the structure is completely within our property... and the corner of the property is moved to extend a little past the corner pin. I am assuming (maybe incorrectly, but not sure) that the structure was built not knowing it encroached the 3 ft... and then the "line of agreement" came about to somehow attempt to keep the structure all on one property. I do not believe any legal written agreement was ever made, and I also believe an agreement would not be possible between us and our neighbors (we don't get along). We wish to put up a fence, but not sure which line to go with... the line est. by the pins, or the line recommended as the "line of agreement". I do not believe an adverse posession claim could be made by either us or our neighbors. My questions are: which line is the actual property line?... and how could I get this "line of agreement" line to be "set-in-stone" so as it is not debated/questioned in the future? A quiet title claim? Do I need to knock-down the concrete structure? or at least the part over the line? Thank-you for your help.