30 Unusual Archaeological Finds In The US We Still Can’t Explain

9. MYSTERIOUS ANCIENT STONE WALLS

The Berkeley Mystery Walls stretch for over 50 miles along the hills from Berkeley to San Jose. The structure is a series of stones in place together, and it’s a big mystery because no one knows who built them. According to reports, the walls were already there when the Spanish settlers arrived in the area. The arrangement appears to be of prehistoric origin, but no one knows its purpose since they’re not high enough to serve as an enclosure or for defence.