That structure is a 20-30-foot long, 8-9-foot tall stone dam that rises above a granite bedrock just behind homes along a creek north of 440.
The landowner, who prefers not to be identified, said he believes it was built prior to the Civil War. Its incredible masonry work, known as a "dry stack," was quarried and fit together so tightly without mortar, that even today it does not leak when powerful storms cause torrents of water to pour around it.
Parts of the stone dam were demolished in the late 1960s to build a neighborhood and lay sewer lines, but much of it and an adjacent earthen dam remain more than 100 years later.
Historical societies in Wake County date it possibly to the 18th century when it served perhaps as a gristmill. There is little official information to accurately provide details and age of the dam, but it's nevertheless a curiosity to those who live near it.
The resident whose property it partially sits on wants to keep its exact location private, as to preserve its integrity and reduce vandalism to the stonework. In short, he doesn't want sightseers trespassing on his land.
For now, it will have to remain a mystery until it's publicly recognized as having historical significance and finds a way to allow curious visitors through public access.