What is Berkeley Mystery Walls?

Berkeley Mystery Walls, also known as East Bay Walls, are found throughout the hills from Berkeley to San Jose. These stone walls are said to be constructed from different shapes and sizes of boulders and are as tall as five feet in some places. The Mystery Walls are usually found in inaccessible places where they run in broken sections. Talking about the length, these wall ranges from a few meters to over a half-mile. The walls are very old, and their exact age remains undetermined.